Squarilium compound and liquid crystal composition containing the same

ABSTRACT

A squarilium compound represented by the following formula (I) and a liquid crystal composition containing the same are disclosed: ##STR1## wherein X and Y each represents ##STR2## wherein R 1  represents a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group or a substituted or unsubstituted aralkyl group; R 2 , R 3  and R 4  each represents a hydrogen atom, an alkyl group or a substituted or unsubstituted alkoxy group; R 5  represents a hydrogen atom, an alkyl group, an aralkyl group or an aryl group; ring A represents a cyclic alkylene; ring B represents a substituted or unsubstituted aromatic ring; and ring C represents a heterocyclic ring containing one or two of a nitrogen atom, an oxygen atom and a sulfur atom; with proviso that X and Y are not the same when either one of them represents ##STR3## and a liquid crystal composition containing the squarilium compound of the formula (I). The squarilium compound (I) are soluble in a wide variety of solvents and resistant to light, and their maximum absorption wavelengths in these solvents are in the ranges of from 700 to 900 nm.

This is a continuation of application Ser. No. 228,405 filed Aug. 5,1988, now abandoned, which is a continuation of Ser. No. 809,674 filedDec. 16, 1985, now abandoned.

FIELD OF THE INVENTION

This invention relates to a squarilium compound and a liquid crystalcomposition containing the same.

BACKGROUND OF THE INVENTION

An information recording system using laser beams has recently beenstudied, wherein a liquid crystal having dissolved therein a compoundwhich absorbs a laser beam of specific wavelengths is heated byirradiation of such a laser beam, whereupon the state of the irradiatedportion is changed, for example, from an isotropically aligned state toa scattered state, as described, e.g., in IBM Tech. Discl. Bull., 21,2007 (1978).

On the other hand, it is known that a squarilium compound hasphotoconductivity and can be used, e.g., as an electric charge generatorfor electrophotographic light-sensitive materials (Japanese PatentApplication (OPI) No. 105536/74, the term "OPI" as herein used referringto "published unexamined application"), a laser beam-absorbing materialfor laser recording liquid crystal display devices (Japanese PatentApplication (OPI) No. 197485/84) and as a recording material forphotodiscs (Japanese Patent Application (OPI) Nos. 46221/81, 217758/83and 129954/84).

However, conventionally known squarilium compounds involve problems ofsolubility such that they are soluble only in limited solvents, such asaprotic polar solvents, e.g., N,N-dimethylformamide,N-methylpyrrolidone, N,N-dimethylacetamide, formamide, dimethylsulfoxide, etc., and also some of them have very poor solubility as inthe case of Compound No. 6 disclosed in Japanese Patent Application(OPI) No. 129954/84. Further, many of these known compounds not onlyhave the maximum absorption wavelengths in their solutions far asidefrom the oscillation wavelengths of semiconductor lasers, i.e., 780 nm,830 nm or 850 nm but also lack in stability due to their insufficientlight-resistance.

The conventional squarilium compounds can, therefore, find only limitedapplications and are not satisfactorily applicable to variousinformation recording materials, particularly those using a laser beamas a light source.

SUMMARY OF THE INVENTION

Accordingly, an object of this invention is to provide a novelsquarilium compound which can eliminate the above-described problemsassociated with the known squarilium compounds, as well as a liquidcrystal composition containing such a novel squarilium compound.

That is, the present invention relates to a squarilium compoundrepresented by the formula (I): ##STR4## wherein X and Y each represents##STR5## wherein R¹ represents a hydrogen atom, an alkyl group, asubstituted or unsubstituted aryl group or a substituted orunsubstituted aralkyl group; R², R³ and R⁴ each represents a hydrogenatom, an alkyl group or a substituted or unsubstituted alkoxy group; R⁵represents a hydrogen atom, an alkyl group, an aralkyl group or an arylgroup; ring A represents a cyclic alkylene; ring B represents asubstituted or unsubstituted aromatic ring; and ring C represents aheterocyclic ring containing one or two of a nitrogen atom, an oxygenatom and a sulfur atom; with proviso that X and Y are not the same wheneither one of them represents ##STR6## and a liquid crystal compositioncontaining the squarilium compound of the formula (I).

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a visible to infrared absorption spectrum of the squariliumcompound according to Example 264 of this invention in a chloroformsolution.

DETAILED DESCRIPTION OF THE INVENTION

The compound represented by the formula (I) according to the presentinvention can easily be prepared by, for example, reacting an azulenederivative represented by the formula (II) or (III):

    X-H                                                        (II)

    Y--H                                                       (III)

wherein X and Y are as defined above, with3,4-dihydroxy-3-cyclobutene-1,2-dione, i.e., squaric acid, representedby the formula: ##STR7## in a solvent.

The solvent which can be used in the above reaction includes alcohols,e.g., methanol, ethanol, 1-propanol, isopropyl alcohol, 1-butanol,2-butanol, amyl alcohol, 1-hexanol, cyclohexanol, 1-heptanol, 1-nonanol,etc.; and mixed solvents of these alcohols and aromatic hydrocarbons,e.g., benzene, toluene, xylene, chlorobenzene, etc.

The reaction temperature is selected from to 150° C., and preferablyfrom 90° to 120° C.

The starting compound represented by the formula (II) or (III) includesthe azulene derivatives as follows:

(a) The position numbering system of the azulene derivatives shown belowis ##STR8## Azulene 1,5,8-Trimethylazulene

1,6,8-Trimethylazulene

4,6,8-Trimethylazulene

6-Isopropyl-4,8-dimethylazulene

6-t-Butyl-4,8-dimethylazulene

1-Methyl-2-ethyl-5-isopropylazulene

1-Methyl-2-ethyl-6-methylazulene

1-Ethyl-2-n-propyl-5-isopropylazulene

1-Ethyl-2-n-propyl-6-isopropylazulene

1-n-Propyl-2-n-butyl-5-isopropylazulene

1-Isopropyl-2-isopropyl-5-isopropylazulene

1-n-Butyl-2-n-pentyl-5-isopropylazulene

1-n-Pentyl-2-n-hexyl-6-isopropylazulene

1-n-Hexyl-2-n-octyl-6-isopropylazulene

1-n-Octyl-2-n-hexyl-6-isopropylazulene

1-n-Decyl-2-n-undecyl-5-isopropylazulene

1,4-Dimethyl-7-isopropylazulene

1-n-Dodecyl-2-n-tridecyl-5-isopropylazulene

1-Methyl-8-methoxyazulene

1-Ethyl-8-methoxyazulene

1-Methyl-5-isopropylazulene

1-Ethyl-5-isopropylazulene

1-n-Propyl-5-isopropylazulene

1-Isopropyl-5-isopropylazulene

1-Butyl-5-isopropylazulene

1-Methyl-6-isopropylazulene

1-Propyl-6-isopropylazulene

1-n-Octyl-5-isopropylazulene

1-n-Decyl-5-isopropylazulene

1-n-Octadecyl-5-isopropylazulene

1-Methyl-5-methyl-8-methylazulene

1-Methyl-6-methyl-8-methylazulene

1-n-Butyl-5-isopropyl-8-methoxyazulene

1-n-Propyl-5-isopropyl-8-n-hexyloxyazulene

1-Ethyl-5-isopropyl-8-n-octadecyloxyazulene

1-n-Pentyl-5-isopropyl-8-ethoxyethoxyazulene

1-n-Tetradecylazulene

1-n-Pentadecylazulene

1-n-Hexadecylazulene

1-n-Heptadecylazulene

1-n-Octadecylazulene

1-n-Nonadecylazulene

1-n-Eicosylazulene

1-n-Heneicosylazulene

1-n-Docosylazulene

1-n-Tricosylazulene

1-n-Tetracosylazulene

1-n-Pentacosylazulene

1-n-Tetradecyl-5-isopropylazulene

1-n-Hexadecyl-5-isopropylazulene

1-n-Heptadecyl-5-isopropylazulene

1-n-octadecyl-5-isopropylazulene

1-n-Eicosyl-5-methylazulene

1-n-Docosyl-5-methylazulene

1-n-Tetracosyl-5-methylazulene

1-n-Pentadecyl-6-isopropylazulene

1-n-Heptadecyl-6-isopropylazulene

1-n-Octadecyl-6-methylazulene

1-n-Heneicosyl-6-methylazulene

1-n-Pentadecyl-8-methoxyazulene

1-n-Heptadecyl-8-methoxyazulene

1-n-Octadecyl-8-methoxyazulene

1-n-Heptadecyl-8-methoxyethoxyazulene

1-n-Heptadecyl-8-heptadecyloxyazulene

1-n-Hexadecyl-5-isopropyl-8-methoxyazulene

1-n-Heptadecyl-5-isopropyl-8-methoxyazulene

1-n-Octadecyl-5-isopropyl-8-methoxyazulene

1-n-Pentadecyl-5-methyl-8-methoxyazulene

1-n-Nonadecyl-5-methyl-8-methoxyethoxyethoxyazulene

1-n-Tetradecyl-6-isopropyl-8-methoxyazulene

1-n-Heptadecyl-6-isopropyl-8-methoxyazulene

1-n-Heptadecyl-6-isopropyl-8-ethoxyazulene

1-n-Octadecyl-6-isopropyl-8-methoxyazulene

1-n-Tetradecyl-5-isopropyl-8-octadecyloxyazulene

1-n-Pentadecyl-2-n-tetradecylazulene

1-n-Tetradecyl-2-n-pentadecylazulene

1-n-Tetradecyl-2-n-pentadecyl-5-isopropylazulene

1-n-Hexadecyl-2-n-heptadecyl-5-isopropylazulene

1-Phenylazulene

1-Phenyl-5-methylazulene

1-Phenyl-6-methylazulene

1-Phenyl-5-isopropylazulene

1-Phenyl-6-isopropylazulene

1-(p-Methylphenyl)-6-isopropylazulene

1-(m-Methylphenyl)-5-isopropylazulene

1-(p-Ethylphenyl)-5-methylazulene

1-(p-Ethylphenyl)-6-isopropylazulene

1-(p-n-Propoxyphenyl)-5-isopropylazulene

1-(p-n-Butylphenyl)-5-isopropylazulene

1-(p-n-Butoxyphenyl)-5-isopropylazulene

1-(p-n-Pentylphenyl)-5-isopropylazulene

1-(p-n-Hexylphenyl)-6-isopropylazulene

1-(p-n-Heptylphenyl)-5-isopropylazulene

1-(p-n-Heptylphenyl)-6-methylazulene

1-(p-n-Octylphenyl)-5-isopropylazulene

1-(p-t-Butylphenyl)-5-isopropylazulene

1-(p-t-Butylphenyl)-6-isopropylazulene

1-(p-Fluorophenyl)-5-isopropylazulene

1-(p-Chlorophenyl)-6-isopropylazulene

1-(m-Bromophenyl)-5-isopropylazulene

1-Benzyl-5-isopropylazulene

1-Benzyl-6-isopropylazulene

1-Benzyl-5-methylazulene

1-(m-Bromobenzyl)-6-methylazulene

1-(p-Methylbenzyl)-5-isopropylazulene

1-(p-n-Butylbenzyl)-5-isopropylazulene

1-(p-n-Hexyloxybenzyl)-6-isopropylazulene

1-(p-n-Octylbenzyl)-6-isopropylazulene

1-Phenethyl-5-isopropylazulene

1-(p-Methylphenethyl)-6-isopropylazulene

1,2-Trimethylene-5-isopropylazulene

1,2-Trimethylene-6-isopropylazulene

1,2-Trimethylene-5-methylazulene

1,2-Trimethylene-6-methylazulene

1,2-Trimethyleneazulene

1,2-Tetramethyleneazulene

1,2-Tetramethylene-5-methylazulene

1,2-Tetramethylene-6-methylazulene

1,2-Tetramethylene-5-isopropylazulene

1,2-Tetramethylene-6-isopropylazulene

1,2-pentamethylene-5-methylazulene

1,2-Pentamethylene-6-methylazulene

1,2-Pentamethylene-5-isopropylazulene

1,2-Pentamethylene-6-isopropylazulene

1,2-Hexamethylene-5-isopropylazulene

1,2-Hexamethylene-6-isopropylazulene

1,2-Decamethylene-5-isopropylazulene

1,2-Decamethylene-6-isopropylazulene

(b) The position numbering system of the following benz[a]azulenederivatives is ##STR9## Benz[a]azulene1,2,3,4-Tetrahydro-3-methyl-benz[a]azulene

1,2,3,4-Tetrahydro-3-t-butyl-benz[a]azulene

7-Isopropyl-benz[a]azulene

8-Isopropyl-benz[a]azulene

3-Ethyl-8-isopropyl-benz[a]azulene

3-t-Butyl-benz[a]azulene

3-t-Butyl-8-isopropyl-benz[a]azulene

3-n-Pentyl-8-isopropyl-benz[a]azulene

3-n-Heptyl-7-methyl-benz[a]azulene

3-n-Heptyl-8-isopropyl-benz[a]azulene

3-n-Octyl-8-isopropyl-benz[a]azulene

2-Methoxy-8-isopropyl-benz[a]azulene

2-n-Butoxy-8-methyl-benz[a]azulene

3-Methoxy-7-isopropyl-benz[a]azulene

3-Methoxy-8-isopropyl-benz[a]azulene

3-Bromo-8-isopropyl-benz[a]azulene

3-Ethyl-5-methoxy-8-isopropyl-benz[a]azulene

3-n-Butyl-5-methoxy-8-isopropyl-benz[a]azulene

3-n-Propyl-5-butoxy-7-isopropyl-benz[a]azulene

5-Ethoxyethoxy-8-isopropyl-benz[a]azulene

3-Ethyl-7-isopropyl-benz[a]azulene

3-n-Propyl-7-isopropyl-benz[a]azulene

3-n-Propyl-8-isopropyl-benz[a]azulene

3-n-Butyl-8-isopropyl-benz[a]azulene

3-n-Hexyl-7-isopropyl-benz[a]azulene

3-n-Heptyl-8-methyl-benz[a]azulene

3-n-Octyl-8-methyl-benz[a]azulene

3-n-Tridecyl-8-methyl-benz[a]azulene

2-n-Butoxy-8-isopropyl-benz,:a]azulene

2-n-Heptyloxy-8-isopropyl-benz[a]azulene

3-Methoxy-8-isopropyl-benz[a]azulene

3-t-Butyl-5-methoxy-8-isopropyl-benz[a]azulene

3-Ethyl-5-n-butoxy-8-isopropyl-benz[a]azulene

3-n-Propyl-5-n-octyloxy-7-isopropyl-benz[a]azulene

5-n-Tridecyloxy-8-isopropyl-benz[a]azulene

2-Methoxyethoxy-8-isopropyl-benz[a]azulene

2-Ethoxyethoxyethoxy-8-isopropyl-benz[a]azulene

5-Methoxyethoxyethoxy-8-isopropyl-benz[a]azulene

3-n-Pentyl-benz[a]azulene

3-n-Heptyl-benz[a]azulene

3-n-Propyl-benz[a]azulene

3-t-Butyl-8-isopropyl-benz[a]azulene

7-Isopropyl-benz[a]azulene

3-n-Hexyl-benz[a]azulene

3-n-Octyl-8-isopropyl-benz[a]azulene

3-n-Pentyl-7-isopropyl-benz[a]azulene

3-n-Butyl-7-isopropyl-benz[a]azulene

(c) The position numbering system of the followingazuleno[1,2-b]thiophene derivatives is ##STR10## Azuleno[1,2-b]thiohene7-Methylazuleno[1,2-b]thiophene

7-Isopropylazuleno[1,2-b]thiophene

6-Methylazuleno[1,2-b]thiophene

6-Isopropylazuleno[1,2-b]thiophene

4-Methoxy-7-isopropylazuleno[1,2-b]thiophene

4-Butoxy-7-isopropylazuleno[1,2-b]thiophene

4-Octyloxy-6-isopropylazuleno[1,2-b]thiophene

4-Ethoxyethoxy-7-isopropylazuleno[1,2-b]thiophene

4-Methoxyethoxyethoxy-7-isopropylazuleno[1,2-b]-thiophene

1,4,8-Trimethylazuleno[1,2-b]thiophene

4-Tridecyloxy-7-isopropylazuleno[1,2-b]thiophene

4-Octadecyloxy-7-isopropylazuleno[1,2-b]thiophene

Azuleno[1,2-b]1,2-dihydroxythiophene

7-Isopropylazuleno[1,2-b]1,2-dihydrothiophene

6-Isopropylazuleno[1,2-b]1,2-dihydrothiophene

7-Methylazuleno[1,2-b]1,2-dihydrothiophene

4-Methoxy-7-isopropylazuleno[1,2-b]1,2-dihydrothiophene

4-Hepthyloxy-7-isopropylazuleno[1,2-b]1,2-dihydrothiophene

4-Octadecyloxy-7-isopropylazuleno[1,2-b]1,2-dihydrothiophene

4-Methoxy-6-isopropylazuleno[1,2-b]1,2-dihydrothiophene

4-Methoxyazuleno[1,2-b]1,2-dihydrothiophene

2-Methyl-7-isopropylazuleno[1,2-b]thiophene

4-Methoxyethoxy-7-isopropylazuleno[1,2-b]1,2-dihydrothiophene

2-Methylazuleno[1,2-b]thiophene

4-Methoxyazuleno[1,2-b]thiophene

1,2-Diphenylazuleno[1,2-b]thiophene

4,6,8-Trimethyl-2-phenylazuleno[1,2-b]thiophene

(d) The position numbering system of the followingazuleno[2,1-b]thiophene derivatives is ##STR11## Azuleno[2,1-b]thiophene7-Methylazuleno[2,1-b]thiophene

7-Isopropylazuleno[2,1-b]thiophene

6-Methylazuleno[2,1-b]thiophene

6-Isopropylazuleno[2,1-b]thiophene

4-Methoxy-7-isopropylazuleno[2,1-b]thiophene

4-Butoxy-7-isopropylazuleno[2,1-b]thiophene

4-Octyloxy-6-isopropylazuleno[2,1-b]thiophene

4-Ethoxyethoxy-7-isopropylazuleno[2,1-b]thiophene

4-Methoxyethoxyethoxy-7-isopropylazuleno[2,1-b]-thiophene

4-Dodecyloxy-7-isopropylazuleno[2,1-b]thiophene

4-Octadecyloxy-7-isopropylazuleno[2,1-b]thiophene

Azuleno[2,1-b]2,3-dihydrothiophene

7-Isopropylazuleno[2,1-b]2,3-dihydrothiophene

6-Isopropylazuleno[2,1-b]2,3-dihydrothiophene

7-Methylazuleno[2,1-b]2,3-dihydrothiophene

4-Methoxy-7-isopropylazuleno[2,1-b]2,3-dihydrothiophene

4-Heptyloxy-7-isopropylazuleno[2,1-b]2,3-dihydrothiophene4-Octadecyloxy-7-isopropylazuleno[2,1-b]2,3-dihydrothiophene

4-Methoxy-6-isopropylazuleno[2,1-b]2,3-dihydrothiophene

4-Methoxyazuleno[2,1-b]2,3-dihydrothiophene

2-Ethoxycarbonylazuleno[2,1-b]thiophene

3-Methylazuleno[2,1-b]thiophene

3-Methoxyazuleno[2,1-b]thiophene

4-Methoxyethoxy-7-isopropylazuleno[2,1-b]2,3-dihydrothiophene

4-Methoxyazuleno[2,1-b]thiophene

(e) The position numbering system of the followingazuleno[1,2-c]thiophene derivatives is ##STR12## Azuleno[1,2-c]thiophene7-Methylazuleno[1,2-c]thiophene

7-Isopropylazuleno[1,2-c]thiophene

6-Methylazuleno[1,2-c]thiophene

6-Isopropylazuleno[1,2-c]thiophene

4-Methoxy-7-isopropylazuleno[1,2-c]thiophene

4-Butoxy-7-isopropylazuleno[1,2-c]thiophene

4-Octyloxy-6-isopropylazuleno[1,2-c]thiophene

4-Ethoxyethoxy-7-isopropylazuleno[1,2-c]thiophene

4-Methoxyethoxyethoxy-7-isopropylazuleno[1,2-c]thiophene

4-Octadecyloxy-7-isopropylazuleno[1,2-c]thiophene

Azuleno[1,2-c]1,3-dihydrothiophene

7-Isopropylazuleno[1,2-c]1,3-dihydrothiophene

6-Isopropylazuleno[1,2-c]1,3-dihydrothiophene

7-Methylazuleno[1,2-c]1,3-dihydrothiophene

4-Methoxy-7-isopropylazuleno[1,2-c]1,3-dihydrothiophene

4-Heptyloxy-7-isopropylazuleno[1,2-c]1,3-dihydrothiophene

4-Octadecyloxy-7-isopropylazuleno[1,2-c]1,3-dihydrothiophene

4-Methoxy-6-isopropylazuleno[1,2-c]1,3-dihydrothiophene

4-Methoxyazuleno[1,2-c,1,3-dihydrothiophene

4-Methoxyethoxy-7-isopropylazuleno[1,2-c]1,3-dihydrothiophene

4-Methoxyazuleno[1,2-c]thiophene

(f) The position numbering system of the following azuleno[1,2-b]furanderivatives is ##STR13## Azuleno[1,2-b]furan 7-Methylazuleno[1,2-b]furan

7-Isopropylazuleno[1,2-b]furan

6-Methylazuleno[1,2-b]furan

6-Isopropylazuleno[1,2-b]furan

4-Methoxy-7-isopropylazuleno[1,2-b]furan

4-Butoxy-7-isopropylazuleno[1,2-b]furan

4-Octyloxy-6-isopropylazuleno[1,2-b]furan

4-Ethoxyethoxy-7-isopropylazuleno[1,2-b]furan

4-Methoxyethoxyethoxy-7-isopropylazuleno[1,2-b]furan

4-Octadecyloxy-7-isopropylazuleno[1,2-b]furan

4-Methoxyazuleno[1,2-b]furan

(g) The position numbering system of the following azuleno[1,2-b]pyrrolederivatives is ##STR14## Azuleno[1,2-b]pyrrole7-Methylazuleno[1,2-b]pyrrole

7-Isopropyl1,2-b]pyrrole

6-Isopropyl[1,2-b]pyrrole

3-Ethoxycarbonylazuleno[1,2-b]pyrrole

3-Ethoxycarbonyl-7-isopropylazuleno[1,2-b]pyrrole

3-Ethoxycarbonyl-6-isopropylazuleno[1,2-b]pyrrole

(h) The position numbering system of the followingazuleno[1,2-c]pyridine derivatives is ##STR15## Azuleno[1,2-c]pyridine8-Methylazuleno[1,2-c]pyridine

8-Isopropylazuleno[1,2-c]pyridine

7-Isopropylazuleno[1,2-c]pyridine

3-Ethoxycarbonylazuleno[1,2-c]1,2,3,4-tetrahydropyridine

3-Ethoxycarbonyl-8-isopropylazuleno[1,2-c]1,2,3,4-tetrahydropyridine

3-Ethoxycarbonyl-7-isopropylazuleno[1,2-c]1,2,3,4-tetrahydropyridine

(i) The position numbering system of the followingazuleno[2,1-c]pyridine derivatives is ##STR16## Azuleno[2,1-c]pyridineMethylazuleno[2,1-c]pyridine

8-Isopropylazuleno[2,1-c]pyridine

7-Isopropylazuleno[2,1-c]pyridine

Azuleno[2,1-c]1,2,3,4-tetrahydropyridine

Azuleno[2,1-c]3,4-dihydropyridine

2-Ethoxycarbonylazuleno[2,1-c]1,2,3,4-tetrahydropyridine

2-Ethoxycarbonyl-8-isopropylazuleno[2,1-c]1,2,3,4-tetrahydropyridine

2-Ethoxycarbonyl-7-isopropylazuleno[2,1-c]1,2,3,4-tetrahydropyridine

(g) The position numbering system of the followingazuleno[1,2-b]pyridine derivatives is ##STR17## Azuleno[1,2-b]pyridine4-Ethoxycarbonylazuleno[1,2-b]1,2,3,4-tetrahydropyridine

4-Ethoxycarbonyl-8-isopropylazuleno[1,2-b]1,2,3,4-tetrahydropyridine

4-Ethoxycarbonyl-7-isopropylazuleno[1,2-b]1,2,3,4-tetrahydropyridine

(k) The position numbering system of the followingazuleno[2,1-b]pyridine derivatives is ##STR18## Azuleno[2,1-b]pyridine2,3-Dichloroazuleno[2,1-b]pyridine

2-Methoxy-3-ethoxycarbonylazuleno[2,1-b]pyridine

2-Methylamino-3-ethoxycarbonylazuleno[2,1-b]pyridine

2-Methoxy-3-cyanoazuleno[2,1-b]pyridine

Among the squarilium compounds represented by the formula (I), thesquarilium compounds represented by the following formulae (IV) to(XXIII) are preferred. ##STR19## wherein R⁶ represents a hydrogen atomor an alkyl group having from 1 to 13 carbon atoms; and R⁷ and R⁸ eachrepresents a hydrogen atom, an alkyl group having from to 13 carbonatoms or an alkoxy group having from 1 to 13 carbon atoms, with provisothat R⁷ and R⁸ are positioned at the 5-, 6- or 8-position. ##STR20##wherein R⁹ represents a substituted or unsubstituted aryl group or asubstituted or unsubstituted aralkyl group; and R¹⁰ represents ahydrogen atom or an alkyl group having from 1 to 13 carbon atoms.##STR21## wherein R¹⁰ is as defined above; and R¹¹ and R¹² eachrepresents an alkyl group having from 1 to 13 carbon atoms. ##STR22##wherein R¹⁰ and ring A are as defined above. ##STR23## wherein R¹⁰ is asdefined above; R¹³ represents a hydrogen atom or a substituted orunsubstituted alkoxy group having from 1 to 13 carbon atoms; and R¹⁴represents a hydrogen atom, a halogen atom, an alkyl group having from 1to 13 carbon atoms or a substituted or unsubstituted alkoxy group havingfrom 1 to 13 carbon atoms; with proviso that at least one of R¹⁰, R¹³and R¹⁴ represents an alkyl group having from 1 to 13 carbon atoms or asubstituted or unsubstituted alkoxy group having from 1 to 13 carbonatoms. ##STR24## wherein R⁶ is as defined above; R^(6') has the samemeanings as defined for R⁶ ; R²², R^(22'), R²³ and R^(23') eachrepresents a hydrogen atom, an alkyl group having from 1 to 13 carbonatoms or a substituted or unsubstituted alkoxy group having from 1 to 13carbon atoms; R²⁴ and R²⁴ ' each represents a hydrogen atom or alkylgroup having from 1 to 13 carbon atoms; with proviso that at least oneof the symmetrical pairs of R⁶ and R^(6') ; R²² and R^(22') ; R²³ andR^(23') ; and R²⁴ and R^(24') comprises different groups. ##STR25##wherein R⁶, R²², R^(22'), R²³, R^(23'), R²⁴ and ring A are as definedabove. ##STR26## wherein R⁶, lR²², lR^(22'), R²³, R^(23'), R²⁴ and ringB are as defined above. ##STR27## wherein R²², R^(22'), R²³, R^(23'),ring A and ring B are as defined above. ##STR28## wherein R²², R^(22'),R²³, R^(23') and ring B are as defined above; and ring B' has the samemeanings as ring B. ##STR29## wherein R¹, r², R³ and R⁵ are as definedabove; and R²⁶, R²⁷ and lR²⁸ each represents an alkyl group. ##STR30##wherein R², r³, ring A, R²⁶, lR²⁷ and R²⁸ are as defined above.##STR31## wherein R², R³, r²⁶, R²⁷, R²⁸ and ring B are as defined above.##STR32## wherein R², R³ and ring C are as defined above; R^(2') has thesame meanings as R² ; R^(3') has the same meanings as R^(3') ; and ringC' has the same meanings as ring C. ##STR33## wherein R², R³, lR^(2'),R^(3') and ring C are as defined above; R^(1') has the same meaning asR¹ ; R^(4') has the same meaning as R⁴ ; and R^(5') has the same meaningas R⁵. ##STR34## wherein R², r³, R^(2'), R^(3'), lR^(4'), ring A andring C are as defined above. ##STR35## wherein R², R³, R^(2'), lR^(3'),R^(4'), ring B and ring C are as defined above. ##STR36## wherein R²,lR³, R^(1'), lR^(2'), lR^(3') and R^(5') are as defined above; and R³⁸and R³⁹ represent a hydrogen atom or an alkyl group having from 14 to 25carbon atoms; with proviso that at least one of R³⁸ and R³⁹ representsan alkyl group having from 14 to 25 carbon atoms. ##STR37## wherein R²,R³, R², R^(3'), R³⁸, R³⁹ and ring B are as defined above; with provisothat at least one of R³⁸ and R³⁹ represents an alkyl group having from14 to 25 carbon atoms. ##STR38## wherein R², R³, R^(2'), R³, R³⁸, R³⁹and ring A are as defined above; with proviso that at least one of R³⁸and R³⁹ represents an alkyl group having from 14 to 25 carbon atoms.

In the above-described formulae (I) to (XXIII), substituents for thesubstituted alkoxy group include an alkoxy group, an alkoxyalkoxy group,an alkoxyalkoxyalkoxy group and the like. The substituted aralkyl groupincludes a benzyl or phenylethyl group substituted with a halogen atom,e.g., a fluorine atom, a chlorine atom, a bromine atom, etc:, an alkylgroup or an alkoxy group. The substituted aryl group includes a phenylgroup, etc. substituted with the same substituents as enumerated for thesubstituted aralkyl group. The heterocyclic ring as represented by ringsC or C' includes a furan ring, a dihydrofuran ring, a thiophene ring, adihydrothiophene ring, a pyrrole ring, a dihydropyrrole ring, a pyrazolering, an imidazole ring, a thiazole ring, a pyridine ring, adihydropyridine ring, a tetrahydropyridine ring, a pyridazine ring, apyrimidine ring, a pyrazine ring, a thiapyran ring, a quinoxaline ring,etc.

In the above-described formula (VIII), at least one of R¹⁰, R¹³ and R¹⁴is an alkyl group having from 1 to 13 carbon atoms or a substituted orunsubstituted alkoxy group having from 1 to 13 carbon atoms as mentionedabove. When all of R¹⁰, R¹³ and R¹⁴ are hydrogen atoms in the formula(VIII), such compounds are limited in application because they aresparingly soluble in the hereinafter described solvents and also showthe maximum absorption at 814 nm (in chloroform) that is far aside fromthe oscillation wavelength of semiconductor lasers, i.e., 780 nm, 830 nmor 850 nm.

In the above-described formula (IX), at least one of the pairs of thesymmetrically positioned substituents, i.e., R⁶ and R^(6';) R²² andR^(22') ; R²³ and R^(23') ; and R²⁴ and R^(24'), comprises differentgroups. If each of all these pairs comprises the same groups, suchcompounds may become sparingly soluble in the solvents hereinafterdescribed and, therefore, find a limited application.

The compounds (I) of the present invention are soluble inhalogen-containing hydrocarbon solvents, e.g., chloroform,dichloromethane, dichloroethane, etc.; ether solvents, e.g., diethylether, dioxane, tetrahydrofuran, dimethoxyethane, etc.; ester solvents,e.g., ethyl acetate, etc.; aromatic hydrocarbon solvents, e.g., benzene,toluene, xylene, chlorobenzenes, etc.; amide solvents, e.g., acetamide,N,N-dimethylacetamide, N-methylpyrrolidone, etc.; alcohol solvents,e.g., methanol, ethanol, methyl cellosolve, etc.; dimethyl sulfoxide;and the like. They also exhibit satisfactory light-resistance.

In addition to the solubility in a wide variety of solvents and goodlight-resistance as described above, the compounds of the presentinvention possess a remarkable industrial value in that the maximumabsorption wavelengths in the above-recited solvents fall within a rangeof from 700 to 900 nm and, in particular, are centered mainly in thevicinity of 780 nm, 830 nm or 850 nm that is an oscillation wavelengthof a semiconductor laser. Therefore, they are expected to be useful inthe field of various information materials utilizing a laser beam, suchas laser beam-absorbing materials for laser recording liquid crystaldisplay devices, electrophotographic light-sensitive materials ofelectrophotographic printers using a laser beam as a light source,recording materials for photodiscs in which an information can berecorded and read-out by a laser beam, infrared-cut filters, and thelike.

The squarilium compounds of the present invention can also be employedin liquid crystal compositions in combination with liquid crystals forthe above-described liquid crystal display devices in which aninformation is recorded by a laser beam.

The liquid crystals which can be used in combination with the squariliumcompounds of this invention include smectic liquid crystals andcholesteric liquid crystals.

Examples of the smectic liquid crystals are biphenyl type liquidcrystals, terphenyl type liquid crystals, cyclohexylcyclohexane typeliquid crystals, biphenylcyclohexane type liquid crystals,cyclohexylbiphenylcyclohexane type liquid crystals, phenylcyclohexylcarboxylate type liquid crystals, cyclohexylcyclohexyl benzoate typeliquid crystals, cyclohexylphenylcyclohexyl carboxylate type liquidcrystals, cyclohexylcyclohexylcyclohexyl carboxylate type liquidcrystals, pyrimidine type liquid crystals, etc. and mixtures thereof

Cholesteric liquid crystals can be obtained by adding an opticallyactive substance to nematic liquid crystals of, for example,cyclohexylcyclohexane type liquid crystals, phenylcyclohexane typeliquid crystals, biphenyl type liquid crystals, terphenyl type liquidcrystals, phenylcyclohexyl carboxylate type liquid crystals, phenylbenzoate type liquid crystals, etc.

The optically active substance to be used includes chiralnematiccompounds wherein an optically active group, e.g., a 2-methylbutylgroup, a 3-methylbutoxy group, a 3-methylpentyl group, a 3-methylpentoxygroup, a 4-methylhexyl group, a 4-methylhexyloxy group, etc., isintroduced to a nematic liquid crystals. Additional examples of theoptically active substance include derivatives of alcohols, e.g.,l-menthol, d-borneol, etc.; derivatives of d-camphor,3-methylcyclohexane, etc.; derivatives of carboxylic acids, e.g.,d-citronellic acid, l-camphoric acid, etc.; derivatives of aldehydes,e.g., d-citronellal, etc.; derivatives of alkenes, e.g., d-linonene,etc.; derivatives of amines, amides or nitriles; and the like.

The liquid crystal compositions in accordance with the present inventioncan contain known dichromic dyes and additives, such as viscosityreducing agent.

The present invention will now be illustrated in greater detail withreference to the following examples, but it should be understood thatthese examples are not limiting the present invention.

EXAMPLE 1

To 0.11 g of 3,4-dihydroxy-3-cyclobutene-1,2-dione was added 15 ml ofn-butyl alcohol, and the mixture was heated to about 100° C. to form asolution. To this solution were added 0.46 g of1-n-propyl-5-isopropylazulene and 10 ml of benzene, and the mixture wasstirred at 95° to 105° C. for about 1 hour while azeotropically removingthe produced water. After cooling, n-hexane was added thereto, and theprecipitated crystals were purified by column chromatography to obtain asquarilium compound having the formula: ##STR39## This compound had amelting point of 241.0° to 243.0° C., and its visible absorptionspectrum in a chloroform solution had a maximum absorption wavelength of726 nm.

The resulting compound was added to cyanooctylbiphenyl (a biphenyl typeliquid crystal having a smectic phase) at a ratio of 0.5% by weight,followed by stirring under heating at 50° C. or higher to thereby forman isotropic liquid showing a maximum absorption spectrum at 739 nm.

The thus prepared liquid (liquid crystal composition) was sealed in anelement composed of upper and lower glass plates with a gap therebetweenbeing 9 μm, in which each of the surfaces having a transparent electrodeand contacting the liquid crystal had been subjected to verticalorientation treatment with a vertically orientating agent,octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride. Theelement was irradiated with a GaAlAs semiconductor laser having anoscillation wavelength at 780 nm in a spot of 10 μm. The irradiated spotgot a rise in temperature, and the liquid crystal portion correspondingto the spot wherein molecules had been regularly oriented in a verticaldirection turned into an isotropic liquid. The irradiation of a laserbeam was interrupted, and the element was cooled. When a halogen lamplight was transmitted through the element and projected on a screen toobtain a 10-fold enlarged projective figure, a black and highly contrastfigure was obtained on the screen through the liquid crystal portionwhere the orientation of the liquid crystal molecules was disturbed.

EXAMPLE 2

In the same manner as described in Example 1, a squarilium compound ofthe formula: ##STR40## was prepared This compound had a melting point of266.5° to 267.0° C. and its absorption spectrum in chloroform showed itsmaximum peak at 732 nm.

The resulting compound was added to a 1:1 mixture of cyanooctylbiphenyland cyanononylbiphenyl in an amount of 0.5% by weight, followed bystirring under heating at 50° C. or higher to thereby form an isotropicliquid having its maximum absorption peak at 740 nm.

Display was carried out in the same manner as described in Example 1 butusing the resulting isotropic liquid. There was obtained a projectedfigure having satisfactory contrast.

EXAMPLES 3 TO 21

In the same manner as described in Example 1, squarilium compounds shownin Table 1 below were prepared, and an isotropic liquid was preparedfrom each of the resulting compounds in the same manner as in Example 1.A maximum absorption wavelength of the isotropic liquid in chloroform(λ_(max)) is shown in Table 1 below.

                  TABLE 1                                                         ______________________________________                                         ##STR41##                                                                    Example             (position)-                                                                              (position)-                                                                           .sup.λ max                      No.     R.sup.6     R.sup.7    R.sup.8 (nm)                                   ______________________________________                                         3      CH.sub.3    (5)-CH(CH.sub.3).sub.2                                                                   H       738                                     4      C.sub.2 H.sub.5                                                                           (5)-CH(CH.sub.3).sub.2                                                                   H       739                                     5      C.sub.3 H.sub.7 (n)                                                                       (5)-CH(CH.sub.3).sub.2                                                                   H       739                                     6      CH(CH.sub.3).sub.2                                                                        (5)-CH(CH.sub.3).sub.2                                                                   H       738                                     7       C.sub.4 H.sub.9 (n)                                                                      (5)-CH(CH.sub.3).sub.2                                                                   H       739                                     8      C.sub.5 H.sub.11 (n)                                                                      (5)-CH(CH.sub.3).sub.2                                                                   H       740                                     9      C.sub.6 H.sub.13 (n)                                                                      (5)-CH(CH.sub.3).sub.2                                                                   H       740                                    10      C.sub.7 H.sub.15 (n)                                                                      (5)-CH(CH.sub.3).sub.2                                                                   H       740                                    11      C.sub.8 H.sub.17 (n)                                                                      (5)-CH(CH.sub.3).sub.2                                                                   H       741                                    12      CH.sub.3    (6)-CH(CH.sub.3).sub.2                                                                   H       740                                    13      C.sub.2 H.sub.5                                                                           (6)-CH(CH.sub.3).sub.2                                                                   H       740                                    14      C.sub.3 H.sub.7 (n)                                                                       (6)-CH(CH.sub.3).sub.2                                                                   H       740                                    15      C.sub.8 H.sub.17 (n)                                                                      (6)-CH(CH.sub.3).sub.2                                                                   H       741                                    16      CH.sub.3    (8)-OCH.sub.3                                                                            H       752                                    17      C.sub.2 H.sub.5                                                                           (8)-OCH.sub.3                                                                            H       752                                    18      C.sub.5 H.sub.11 (n)                                                                      (8)-OCH.sub.3                                                                            H       753                                    19      C.sub.8 H.sub.17 (n)                                                                      (8)-OCH.sub.3                                                                            H       753                                    20      CH.sub.3    (5)-CH.sub.3                                                                             (8)-CH.sub.3                                                                          758                                    21      CH.sub.3    (6)-CH.sub.3                                                                             (8)-CH.sub.3                                                                          756                                    ______________________________________                                    

EXAMPLE 22

To 0.15 g of 3,4-dihydroxy-3-cyclobutene-1,2-dione was added 15 ml ofn-butyl alcohol, and the mixture was heated to about 100° C. to form asolution. To this solution were added 0.65 g (0.0026 mol) of1-phenyl-5-isopropylazulene and 10 ml of benzene, and the mixture washeated at 95° to 105° C. for about 1 hour with stirring whileazeotropically removing the produced water.

The reaction mixture was cooled, and n-hexane was added thereto. Theprecipitated crystals were purified by column chromatography to obtain0.13 g of a compound of the formula: ##STR42## This compound had amelting point of 286.0° to 287.0° C. and its visible absorption spectrumin a chloroform solution had a maximum absorption wavelength of 747 nm.

The resulting compound was dissolved in a cyanobiphenyl type liquidcrystal in a concentration of 0.30% by weight. When the solution wassubjected to light resistance test by ultraviolet irradiation using ablack light ("FL-20SBLB" manufactured by Toshiba Electric Corp.), it wasstable even after 15-hour-irradiation.

EXAMPLE 23

In the same manner as described in Example 22 but replacing the1-phenyl-5-isopropylazulene as used in Example 22 with the equimolaramount (0.68 g) of 1-benzyl-5-isopropylazulene, 0.65 g of a compoundhaving the following formula was obtained: ##STR43##

This compound exhibited satisfactory light resistance in the same lightresistance test as in Example 22.

EXAMPLES 24 TO 41

Compounds shown in Table 2 were prepared in the same manner as describedin Example 22 except for replacing the 1-phenyl-5-isopropylazulene asused in Example 22 with azulene compounds correspondingly having thesame substituents as possessed by the compounds shown in Table 2.

The maximum absorption wavelengths of visible absorption spectra ofthese compounds in their chloroform solutions are shown in Table 2.

                  TABLE 2                                                         ______________________________________                                         ##STR44##                                                                    Example                    (position)-                                                                              .sup.λ max                       No.    R.sup.9             R.sup.10   (nm)                                    ______________________________________                                        24                                                                                    ##STR45##          (5)-CH.sub.3                                                                             746                                     25                                                                                    ##STR46##          H          733                                     26                                                                                    ##STR47##          (6)-CH(CH.sub.3).sub.2                                                                   751                                     27                                                                                    ##STR48##          (5)-CH(CH.sub.3).sub.2                                                                   746                                     28                                                                                    ##STR49##          (5)-CH(CH.sub.3).sub.2                                                                   755                                     29                                                                                    ##STR50##          (5)-CH(CH.sub.3).sub.2                                                                   747                                     30                                                                                    ##STR51##          (5)-CH(CH.sub.3).sub.2                                                                   747                                     31                                                                                    ##STR52##          (5)-CH(CH.sub.3).sub.2                                                                   747                                     32                                                                                    ##STR53##          (6)-CH(CH.sub.3).sub.2                                                                   750                                     33                                                                                    ##STR54##          (5)-CH.sub.3                                                                             724                                     34                                                                                    ##STR55##          (6)-CH.sub.3                                                                             729                                     35                                                                                    ##STR56##          (6)-CH(CH.sub.3).sub.2                                                                   729                                     36                                                                                    ##STR57##          (5)-CH(CH.sub.3).sub.2                                                                   725                                     37                                                                                    ##STR58##          (5)-CH(CH.sub.3).sub.2                                                                   725                                     38                                                                                    ##STR59##          (5)-CH(CH.sub.3).sub.2                                                                   726                                     39                                                                                    ##STR60##          (6)-CH(CH.sub.3).sub.2                                                                   730                                     40                                                                                    ##STR61##          (5)-CH(CH.sub.3).sub.2                                                                   725                                     41                                                                                    ##STR62##          (5)-CH(CH.sub.3).sub.2                                                                   756                                     ______________________________________                                    

EXAMPLE 42

To 0.12 g of 3,4-dihydroxy-3-cyclobutene-1,2-dione was added 15 ml ofn-butyl alcohol, and the mixture was heated to about 100° C. to form asolution. To the solution were added 0.43 g of1,2-trimethylene-5-isopropylazulene and 10 ml of benzene, and theresulting mixture was heated to 95° to 105° C. for about 1 hour understirring while azeotropically removing the produced water.

After cooling, n-hexane was added to the reaction mixture, and theprecipitated crystals were purified column chromatography to obtain acompound of the formula: ##STR63## This compound had a melting point of269.0° to 270.0° C. and its visible absorption spectrum in a chloroformsolution had a maximum absorption wavelength of 742 nm.

The compound exhibited stability in the same light resistance test as inExample 22.

EXAMPLES 43 TO 56

Compounds shown in Tables 3 and 4 were prepared in the same manner asdescribed in Example 42 except for replacing the1,2-trimethylene-5-isopropylazulene with corresponding azulene compoundshaving the same substituents as in the compounds of Tables 3 and 4,respectively.

The maximum absorption wavelengths of visible absorption spectra ofthese compounds in their chloroform solutions are shown in Tables 3 and4, respectively.

                  TABLE 3                                                         ______________________________________                                         ##STR64##                                                                    Example                       (position)-                                                                            .sup.λ max                      No.    R.sup.12   R.sup.11    R.sup.10 (nm)                                   ______________________________________                                        43     C.sub.2 H.sub.5                                                                          CH.sub.3    (5)-CH(CH.sub.3).sub.2                                                                 758                                    44     C.sub.3 H.sub.7 (n)                                                                      C.sub.2 H.sub.5                                                                           (5)-CH(CH.sub.3).sub.2                                                                 758                                    45     C.sub.4 H.sub.9 (n)                                                                      C.sub.3 H.sub.7 (n)                                                                       (5)-CH(CH.sub.3).sub.2                                                                 758                                    46     C.sub.5 H.sub.11 (n)                                                                      C.sub.4 H.sub.9 (n)                                                                      (5)-CH(CH.sub.3).sub.2                                                                 758                                    47     C.sub.6 H.sub.13 (n)                                                                     C.sub.5 H.sub.11 (n)                                                                      (6)-CH(CH.sub.3).sub.2                                                                 763                                    48     C.sub.8 H.sub.17 (n)                                                                     C.sub.7 H.sub.15 (n)                                                                      (6)-CH(CH.sub.3).sub.2                                                                 763                                    49     C.sub.11 H.sub.23 (n)                                                                    C.sub.10 H.sub.21 (n)                                                                     (5)-CH(CH.sub.3).sub.2                                                                 763                                    50     C.sub.13 H.sub.27 (n)                                                                    C.sub.12 H.sub.25 (n)                                                                     (5)-CH(CH.sub.3).sub.2                                                                 763                                    ______________________________________                                    

                  TABLE 4                                                         ______________________________________                                         ##STR65##                                                                    Example 1,2-Alkylene Group          .sup.λ max                         No.     for Forming Ring A                                                                            (position)-R.sup. 10                                                                      (nm)                                      ______________________________________                                        51      (CH.sub.2 ) .sub.3                                                                            (5)-CH.sub.3                                                                              742                                       52      (CH.sub.2 ) .sub.3                                                                            (6)-CH(CH.sub.3).sub.2                                                                    745                                       53      (CH.sub.2 ) .sub.4                                                                            H           742                                       54      (CH.sub.2 ) .sub.4                                                                            (5)-CH.sub.3                                                                              758                                       55                                                                                     ##STR66##      (5)-CH(CH.sub.3).sub.2                                                                    758                                       56      (CH.sub.2 ) .sub.4                                                                            (6)-CH(CH.sub.3).sub.2                                                                    761                                       ______________________________________                                    

EXAMPLE 57

To 0.038 g of 3,4-dihydroxy-3-cyclobutene-1,2-dione was added 20 ml ofn-butyl alcohol, and the mixture was heated to about 100° C. to form asolution. To the solution were added 0.15 g of8-isopropyl-benz[a]azulene and 15 ml of benzene, and the mixture wasstirred at 95 to 105° C. for about 1 hour while azeotropically removingthe produced water. After cooling, n-hexane was added to the reactionmixture, and the precipitated crystals were purified by columnchromatography to obtain 0.16 g of a compound of the formula: ##STR67##This compound had a melting point of 194° to 195° C., and its absorptionspectrum in a chloroform solution showed the maximum absorption at 823nm.

EXAMPLE 58

In the same manner as described in Example 57 except for replacing the8-isopropyl-benz[a]azulene as used in Example 57 with the equimolaramount of 3-ethyl-8-isopropyl-benz[a]azulene, a compound of the formula:##STR68## was obtained. This compound had a melting point of to 196° C.,and its absorption spectrum in a chloroform solution had the maximumabsorption wavelength at 836 nm.

EXAMPLE 59

In the same manner as described in Example 57 except for replacing the8-isopropyl-benz[a]azulene as used in Example 57 with the equimolaramount of 3-t-butyl-benz[a]azulene and recrystallizing the crudecrystals from n-butanol, a compound of the formula: ##STR69## wasobtained This compound had a melting point of 310° to 311° C., and itsabsorption spectrum in a chloroform solution showed the maximumabsorption wavelength of 823 nm.

EXAMPLES 60 to 86

In the same manner as described in Example 57, 27 squarilium compoundsas shown in Table 5 below were prepared. Structures and maximumabsorption wavelengths in chloroform solutions of these compounds arealso shown in Table 5.

                                      TABLE 5                                     __________________________________________________________________________     ##STR70##                                                                    Example                   (position)-                                                                          .sup.λ max                            No.   (position)-R.sup. 14                                                                    (position)-R.sup. 13                                                                    R.sup.10                                                                             (nm)                                         __________________________________________________________________________    60    (3)-C.sub.3 H.sub.7 (n)                                                                 H         (8)-C.sub.3 H.sub.7 (iso)                                                            836                                          61    (3)-C.sub.4 H.sub.9 (n)                                                                 H         (8)-C.sub.3 H.sub.7 (iso)                                                            836                                          62    (3)-C.sub.5 H.sub. 11 (n)                                                               H         (8)-C.sub.3 H.sub.7 (iso)                                                            836                                          63    (3)-C.sub.6 H.sub.13 (n)                                                                H         (7)-C.sub.3 H.sub.7 (iso)                                                            841                                          64    (3)-C.sub.7 H.sub.15 (n)                                                                H         (8)-CH.sub.3                                                                         836                                          65    (3)-C.sub.7 H.sub.15 (n)                                                                H         (7)-CH.sub.3                                                                         841                                          66    (3)-C.sub.7 H.sub.15 (n)                                                                H         (8)-C.sub.3 H.sub.7 (iso)                                                            836                                          67    (3)-C.sub.8 H.sub.17 (n)                                                                H         (8)-CH.sub.3                                                                         836                                          68    (3)-C.sub.13 H.sub.27 (n)                                                               H         (8)-CH.sub.3                                                                         836                                          69    (2)-OCH.sub.3                                                                           H         (8)-C.sub.3 H.sub.7 (iso)                                                            839                                          70    (2)-OC.sub.4 H.sub.9 (n)                                                                H         (8)-C.sub.3 H.sub.7 (iso)                                                            839                                          71    (2)-OC.sub.7 H.sub.15 (n)                                                               H         (8)-CH.sub. 3                                                                        839                                          72    (3)-OCH.sub.3                                                                           H         (7)-C.sub.3 H.sub.7 (iso)                                                            847                                          73    (3)-OCH.sub.3                                                                           H         (8)-C.sub.3 H.sub.7 (iso)                                                            843                                          74    (3)-Br    H         (8)-C.sub.3 H.sub.7 (iso)                                                            835                                          75    (3)-C.sub.2 H.sub.5                                                                     (5)-OCH.sub.3                                                                           (8)-C.sub.3 H.sub.7 (iso)                                                            839                                          76    (3)-C.sub.4 H.sub.9 (tert)                                                              (5)-OCH.sub.3                                                                           (8)-C.sub.3 H.sub.7 (iso)                                                            839                                          77    (3)-C.sub.4 H.sub.9 (n)                                                                 (5)-OCH.sub.3                                                                           (8)-C.sub.3 H.sub.7 (iso)                                                            839                                          78    (3)-C.sub.2 H.sub.5                                                                     (5)-OC.sub.4 H.sub. 9 (n)                                                               (8)-C.sub.3 H.sub.7 (iso)                                                            839                                          79    (3)-C.sub.3 H.sub.7 (n)                                                                 (5)-OC.sub.8 H.sub.17 (n)                                                               (7)-C.sub.3 H.sub.7 (iso)                                                            844                                          80    H         (5)-OC.sub.13 H.sub.27 (n)                                                              (8)-C.sub.3 H.sub.7 (iso)                                                            826                                          81    (2)-OC.sub.2 H.sub.4 OCH.sub.3                                                          H         (8)-C.sub.3 H.sub.7 (iso)                                                            839                                          82    (2)-O(C.sub.2 H.sub.4 O).sub.2 C.sub.2 H.sub.5                                          H         (8)-C.sub.3 H.sub.7 (iso)                                                            839                                          83    H         (5)-OC.sub.2 H.sub.4 OC.sub.2 H.sub.5                                                   (8)-C.sub.3 H.sub.7 (iso)                                                            826                                          84    H         (5)-O(C.sub.2 H.sub.4 O).sub.2 CH.sub.3                                                 (8)-C.sub.3 H.sub.7 (iso)                                                            826                                          85    (3)-C.sub.5 H.sub.11 (n)                                                                H         H      823                                          86    (3)-C.sub.7 H.sub.15 (n)                                                                H         H      823                                          __________________________________________________________________________

EXAMPLE 87

To 0.11 g of 3,4-dihydroxy-3-cyclobutene-1,2-dione was added 30 ml ofn-butyl alcohol, and the mixture was heated to about 100° C. to form asolution. To this solution were added 0.20 g of1-methyl-4-methyl-7-isopropylazulene, 0.23 g of1-n-butyl-5-isopropylazulene and 20 ml of benzene, and the resultingsolution was stirred at 95° to 105° C. for about 1 hour whileazeotropically removing the produced water. After cooling, the reactionsolution was subjected to column chromatography to obtain 0.01 g of acompound of the formula: ##STR71## This compound had a melting point of105.0° to 107.0° C., and the maximum absorption wavelength of itsabsorption spectrum in a chloroform solution was 755 nm.

EXAMPLE 88

In the same manner as described in Example 87 but replacing the1-n-butyl-5-isopropylazulene as used in Example 87 with the equimolaramount of 8-isopropylbenz[a]azulene, a compound of the following formulawas obtained: ##STR72## This compound had a melting point of 129.0° to130.0° C., and the maximum absorption wavelength of its absorptionspectrum in a chloroform solution was 796 nm.

EXAMPLES 89 TO 147

In the same manner as described in Example 87, squarilium compounds asshown in Tables 6 to 10 were prepared. Structures and maximum absorptionwavelengths in chloroform solutions of these compounds are also shown inTables 6 to 10 below.

                                      TABLE 6                                     __________________________________________________________________________     ##STR73##                                                                                                                                λ.sub.m                                                                ax                Example No.                                                                          R.sup.24                                                                          R.sup.6                                                                             (position)-R.sup.22                                                                  (position)-R.sup.23                                                                  R.sup.24'                                                                            R.sup.6'                                                                             (position)-R.sup.22'                                                                  (position)-R.sup.23'                                                                 (nm)              __________________________________________________________________________    89      H  CH.sub.3                                                                            (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7                                                                  C.sub.2 H.sub.5                                                                      CH.sub.3                                                                             (5')-C.sub.3 H.sub.7                                                                  Hiso)  763               90     H   CH.sub.3                                                                            (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7                                                                  C.sub.3 H.sub.7 (n)                                                                  C.sub.2 H.sub.5                                                                      (5')-C.sub.3 H.sub.7                                                                  Hiso)  763               91     H   CH.sub.3                                                                            (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7                                                                  C.sub.4 H.sub.9 (n)                                                                  C.sub.3 H.sub.7 (n)                                                                  (5')-C.sub.3 H.sub.7                                                                  Hiso)  763               92     H   CH.sub.3                                                                            (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7                                                                  C.sub.5 H.sub.11 (n)                                                                 C.sub.4 H.sub.9 (n)                                                                  (5')-C.sub.3 H.sub.7                                                                  Hiso)  763               93     H   CH.sub.3                                                                            (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7                                                                  C.sub.6 H.sub.13 (n)                                                                 C.sub.5 H.sub.11 (n)                                                                 (6')-C.sub.3 H.sub.7                                                                  Hiso)  766               94     H   CH.sub.3                                                                            (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7                                                                  C.sub.8 H.sub.17 (n)                                                                 C.sub.7 H.sub.15 (n)                                                                 (5')-C.sub.3 H.sub.7                                                                  Hiso)  766               95     H   CH.sub.3                                                                            (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7                                                                  C.sub.11 H.sub.23 (n)                                                                C.sub.10 H.sub.21 (n)                                                                (5')-C.sub.3 H.sub.7                                                                  Hiso)  766               96     H   CH.sub.3                                                                            (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7                                                                  C.sub.13 H.sub.27 (n)                                                                C.sub.12 H.sub.25 (n)                                                                (5')-C.sub.3 H.sub.7                                                                  Hiso)  766               97     H   CH.sub.3                                                                            (5)-CH.sub.3                                                                         (8)-CH.sub.3                                                                         C.sub.2 H.sub.5                                                                      CH.sub.3                                                                             (5')-C.sub.3 H.sub.7                                                                  Hiso)  758               98     H   CH.sub.3                                                                            (6)-CH.sub.3                                                                         (8)-CH.sub.3                                                                         C.sub.3 H.sub.7 (n)                                                                  C.sub.2 H.sub.5                                                                      (5')-C.sub.3 H.sub.7                                                                  Hiso)  757               99     H   CH.sub.3                                                                            (6)-C.sub.3 H.sub.7 (iso)                                                            H      C.sub.4 H.sub.9 (n)                                                                  C.sub.3 H.sub.7 (n)                                                                  (5')-C.sub.3 H.sub.7                                                                  Hiso)  749               100    H   C.sub.2 H.sub.5                                                                     (6)-C.sub.3 H.sub.7 (iso)                                                            H      C.sub.5 H.sub.11 (n)                                                                 C.sub.4 H.sub.9 (n)                                                                  (5')-C.sub.3 H.sub.7                                                                  Hiso)  749               101    H   C.sub. 3 H.sub.7 (n)                                                                (6)-C.sub.3 H.sub.7 (iso)                                                            H      C.sub.6 H.sub.13 (n)                                                                 C.sub.5 H.sub.11 (n)                                                                 (6')-C.sub.3 H.sub.7                                                                  Hiso)  752               __________________________________________________________________________

                                      TABLE 7                                     __________________________________________________________________________     ##STR74##                                                                    Example                    1',2'-Alkylene Group     λ.sub.max          No.  R.sup.24                                                                          R.sup.6                                                                           (position)-R.sup.22                                                                  (position)-R.sup.23                                                                  for Forming Ring A'                                                                      (position)-R.sup.22'                                                                 (position)-R.sup.23'                                                                 (nm)                      __________________________________________________________________________    102  H   CH.sub.3                                                                          (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7                                                                   (CH.sub.2 ) .sub.3                                                                      (5')-CH.sub.3                                                                        H      755                       103  H   CH.sub.3                                                                          (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7                                                                  (CH.sub.2 ) .sub.3                                                                       (6')-C.sub.3 H.sub.7 (iso)                                                           H      757                       104  H   CH.sub.3                                                                          (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7                                                                  (CH.sub.2 ) .sub.4                                                                       H      H      755                       105  H   CH.sub.3                                                                          (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7                                                                  (CH.sub.2 ) .sub.4                                                                       (5')-CH.sub.3                                                                        H      763                       106  H   CH.sub.3                                                                          (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7 (iso)                                                             ##STR75## (5')-C.sub.3 H.sub.7 (iso)                                                           H      763                       107  H   CH.sub.3                                                                          (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7 (iso)                                                            (CH.sub.2 ) .sub.4                                                                       (6')-C.sub.3 H.sub.7 (iso)                                                           H      765                       __________________________________________________________________________

                                      TABLE 8                                     __________________________________________________________________________     ##STR76##                                                                    Example                       1',2'-Alkylene Group          λ.sub.m                                                                ax                No.  R.sup.24                                                                          R.sup.6                                                                              (position)-R.sup.22                                                                  (position)-R.sup.23                                                                  for Forming Ring B                                                                         (position)-R.sup.22'                                                                    (position)-R.sup.23'                                                                 (nm)              __________________________________________________________________________    108  H   CH.sub.3                                                                             (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7 (iso)                                                             ##STR77##   (5')-C.sub.3 H.sub.7 (iso)                                                              H      802               109  H   CH.sub.3                                                                             (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7 (iso)                                                             ##STR78##   (5')-C.sub.3 H.sub.7 (iso)                                                              H      802               110  H   CH.sub.3                                                                             (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7 (iso)                                                             ##STR79##   (5')-C.sub.3 H.sub.7 (iso)                                                              H      802               111  H   CH.sub.3                                                                             (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7 (iso)                                                             ##STR80##   (6')-C.sub.3 H.sub.7 (iso)                                                              H      805               112  H   CH.sub.3                                                                             (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7 (iso)                                                             ##STR81##   (5')-CH.sub.3                                                                           H      802               113  H   CH.sub.3                                                                             (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7 (iso)                                                             ##STR82##   (6')-CH.sub.3                                                                           H      805               114  H   CH.sub.3                                                                             (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7 (iso)                                                             ##STR83##   (5')-C.sub.3 H.sub.7 (iso)                                                              H      802               115  H   CH.sub.3                                                                             (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7 (iso)                                                             ##STR84##   (5')-CH.sub.3                                                                           H      802               116  H   CH.sub.3                                                                             (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7 (iso)                                                             ##STR85##   (5')-CH.sub.3                                                                           H      802               117  H   CH.sub.3                                                                             (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7 (iso)                                                             ##STR86##   (5')-C.sub.3 H.sub.7 (iso)                                                              H      804               118  H   CH.sub.3                                                                             (4)-CH.sub.3                                                                         (7)-C.sub.3 H.sub.7 (iso)                                                             ##STR87##   (5')-C.sub.3 H.sub.7 (iso)                                                              H      804               119  H   CH.sub.3                                                                             (8)-OCH.sub.3                                                                        H                                                                                     ##STR88##   (5')-CH.sub.3                                                                           H      796               120  H   C.sub.2 H.sub.5                                                                      (8)-OCH.sub.3                                                                        H                                                                                     ##STR89##   (6')-C.sub.3 H.sub.7 (iso)                                                              H      800               121  H   C.sub.5 H.sub.11 (n)                                                                 (8)-OCH.sub.3                                                                        H                                                                                     ##STR90##   (5')-C.sub.3 H.sub.7 (iso)                                                              H      798               122  H   C.sub.8 H.sub.17 (n)                                                                 (8)-OCH.sub.3                                                                        H                                                                                     ##STR91##   (5')-C.sub.3 H.sub.7 (iso)                                                              H      794               123  H   CH.sub.3                                                                             (5)-C.sub.3 H.sub.7 (iso)                                                            H      CHCHCHCH     (8')-OC.sub.13 H.sub.27                                                                 (5')-C.sub.3 H.sub.7                                                          (iso)  782               124  H   C.sub.2 H.sub.5                                                                      (5)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                     ##STR92##   (5')-C.sub.3 H.sub.7 (iso)                                                              H      789               125  H   C.sub.3 H.sub.7 (iso)                                                                (5)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                     ##STR93##   (5')-C.sub.3 H.sub.7 (iso)                                                              H      789               126  H   C.sub.5 H.sub.11 (n)                                                                 (5)-C.sub.3 H.sub.7 (iso)                                                            H      CHCHCHCH     (8')-OC.sub.2 H.sub.4 OC.sub.2                                                H.sub.5   (5')-C.sub.3 H.sub.7                                                          (iso)  783               127  H   C.sub.7 H.sub.15 (n)                                                                 (5)-C.sub.3 H.sub.7 (iso)                                                            H      CHCHCHCH     (8')-O(C.sub.2 H.sub.4                                                        O).sub.2 CH.sub.3                                                                       (5')-C.sub.3 H.sub.7                                                          (iso)  783               128  H   CH.sub.3                                                                             (6)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                     ##STR94##   H         H      782               129  H   C.sub.2 H.sub.5                                                                      (6)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                     ##STR95##   H         H      782               __________________________________________________________________________       PG,65

                                      TABLE 9                                     __________________________________________________________________________     ##STR96##                                                                    Example                                                                            1,2-Alkylene Group       1',2'-Alkylene Group        λ.sub.max    No.  for Forming Ring A                                                                      (position)-R.sup.22                                                                  (position)-R.sup.23                                                                   for Forming Ring B'                                                                        (position)-R.sup.22'                                                                  (position)-R.sup.23'                                                                 (nm)                __________________________________________________________________________    130  (CH.sub.2 (5)-CH.sub.3                                                                         H                                                                                      ##STR97##   (8')-OCH.sub.3                                                                        (5')-C.sub.3 H.sub.7                                                          (iso)  791                 131  (CH.sub.2 ) .sub.3                                                                      (6)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR98##   (8')-OCH.sub.3                                                                        (5')-C.sub.3 H.sub.7                                                          (iso)  792                 132  (CH.sub.2 ) .sub.4                                                                      H      H                                                                                      ##STR99##   (8')-OCH.sub.3                                                                        (5')-C.sub.3 H.sub.7                                                          (iso)  791                 133  (CH.sub.2 ) .sub.4                                                                      (5)-CH.sub.3                                                                         H                                                                                      ##STR100##  (8')-OC.sub.4 H.sub.9 (n)                                                             (5')-C.sub.3 H.sub.7                                                          (iso)  799                 134  (CH.sub.2 ) .sub.4                                                                      (6)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR101##  (8')-OC.sub.8 H.sub.17                                                                (6')-C.sub.3 H.sub.7                                                          (iso)  803                 __________________________________________________________________________

                                      TABLE 10                                    __________________________________________________________________________     ##STR102##                                                                   __________________________________________________________________________    Example                                                                            1,2-Alkylene Group          1',2'-Alkylene Group     λ.sub.max    No.  for Forming Ring B                                                                           (position)-R.sup.22                                                                  R.sup.23                                                                            for Forming Ring B'                                                                        (position)-R.sup.22'                                                                  R.sup.23'                                                                         (nm)                __________________________________________________________________________    135  CHCHCHCH       H      H     CHCHCHCH     (5')-C.sub.3 H.sub.7                                                                  Hiso)                                                                             819                 136                                                                                 ##STR103##    H      H     CHCHCHCH     (5')-C.sub.3 H.sub.7                                                                  Hiso)                                                                             823                 137                                                                                 ##STR104##    H      H                                                                                    ##STR105##  (5')-C.sub.3 H.sub.7                                                                  Hiso)                                                                             830                 138  CHCHCHCH       (5)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                    ##STR106##  (5')-C.sub.3 H.sub.7                                                                  Hiso)                                                                             830                 139                                                                                 ##STR107##    (5)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                    ##STR108##  (5')-C.sub.3 H.sub.7                                                                  Hiso)                                                                             836                 __________________________________________________________________________    Example                                                                            1,2-Alkylene Group          1',2'-Alkylene Group       λ.sub.m                                                                ax                No.  for Forming Ring B                                                                         (position)-R.sup.22                                                                  (position)-R.sup.23                                                                   for Forming Ring B'                                                                        (position)-R.sup.22'                                                                 (position)-R.sup.23'                                                                 (nm)              __________________________________________________________________________    140                                                                                 ##STR109##  H      H       CHCHCHCH     (6')-C.sub.3 H.sub.7                                                                 Hiso)  825               141                                                                                 ##STR110##  H      H                                                                                      ##STR111##  (6')-C.sub.3 H.sub.7                                                                 Hiso)  833               142  CHCHCHCH     (5)-C.sub.3 H.sub.7 (iso)                                                            H       CHCHCHCH     (6')-C.sub.3 H.sub.7                                                                 Hiso)  826               143                                                                                 ##STR112##  (5)-C.sub.3 H.sub.7 (iso)                                                            H       CHCHCHCH     (6')-C.sub.3 H.sub.7                                                                 Hiso)  834               144  CHCHCHCH     (5)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR113##  (6')-C.sub.3 H.sub.7                                                                 Hiso)  833               145                                                                                 ##STR114##  (5)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR115##  (6')-C.sub.3 H.sub.7                                                                 Hiso)  839               146  CHCHCHCH     (6)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR116##  (6')-C.sub.3 H.sub.7                                                                 Hiso)  836               147                                                                                 ##STR117##  (6)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR118##  (6')-C.sub.3 H.sub.7                                                                 Hiso)  844               __________________________________________________________________________      EXAMPLE 148

To 0.11 g of 3,4-dihydroxy-3-cyclobutene-1,2-dione was added 30 ml ofn-butyl alcohol, and the mixture was heated to about 100° C. to form asolution. To the solution were added 0.20 g of1,4-dimethyl-7-isopropylazulene, 0.17 g of 4,6,8-trimethylazulene and 20ml of toluene, and the mixture was stirred at 105° to 110° C. for about1 hour while azeotropically removing the produced water. After cooling,the reaction mixture was purified by column chromatography to obtain0.05 g of a compound of the formula: ##STR119##

This compound had a melting point of 232° to 233° C., and its absorptionspectrum in a chloroform solution showed the maximum absorption at 744nm.

EXAMPLES 149 TO 180

In the same manner as described in Example 148, squarilium compoundsshown in Tables 11 to 13 below were prepared. Their structures and themaximum

                                      TABLE 11                                    __________________________________________________________________________     ##STR120##                                                                   Example                                              λ.sub.max         No.  R.sup.28                                                                          R.sup.27                                                                             R.sup.26                                                                          R.sup.5                                                                              R.sup.1   (position)-R.sup.2                                                                     (position)-R.sup.3                                                                   (nm)                     __________________________________________________________________________    149  CH.sub.3                                                                          CH.sub.3                                                                             CH.sub.3                                                                          C.sub.2 H.sub.5                                                                      CH.sub.3  (5)-C.sub.3 H.sub.7 (iso)                                                              H      740                      150  CH.sub.3                                                                          CH.sub.3                                                                             CH.sub.3                                                                          C.sub. 3 H.sub.7 (n)                                                                 C.sub.2 H.sub.5                                                                         (5)-C.sub.3 H.sub.7 (iso)                                                              H      740                      151  CH.sub.3                                                                          CH.sub.3                                                                             CH.sub.3                                                                          C.sub.4 H.sub.9 (n)                                                                  C.sub.3 H.sub.7 (n)                                                                     (5)-C.sub.3 H.sub.7 (iso)                                                              H      740                      152  CH.sub.3                                                                          CH.sub.3                                                                             CH.sub.3                                                                          C.sub.6 H.sub.13 (n)                                                                 C.sub.5 H.sub.11 (n)                                                                    (6)-C.sub.3 H.sub.7 (iso)                                                              H      743                      153  CH.sub.3                                                                          CH.sub.3                                                                             CH.sub.3                                                                          C.sub.8 H.sub.17 (n)                                                                 C.sub.7 H.sub.15 (n)                                                                    (6)-C.sub.3 H.sub.7 (iso)                                                              H      743                      154  CH.sub.3                                                                          CH.sub.3                                                                             CH.sub.3                                                                          C.sub.5 H.sub.11 (n)                                                                 C.sub.4 H.sub.9 (n)                                                                     (5)-C.sub.3 H.sub.7 (iso)                                                              H      740                      155  CH.sub.3                                                                          CH.sub.3                                                                             CH.sub.3                                                                          C.sub.11 H.sub.23 (n)                                                                C.sub.10 H.sub.21 (n)                                                                   (5)-C.sub.3 H.sub.7 (iso)                                                              H      740                      156  CH.sub.3                                                                          C.sub.3 H.sub.7 (iso)                                                                CH.sub.3                                                                          C.sub.13 H.sub.27 (n)                                                                C.sub.12 H.sub.25 (n)                                                                   (5)-C.sub.3 H.sub.7 (iso)                                                              H      740                      157  CH.sub.3                                                                          CH.sub.3                                                                             CH.sub.3                                                                          H      CH.sub.3  (5)-C.sub.3 H.sub.7 (iso)                                                              H      724                      158  CH.sub.3                                                                          CH.sub.3                                                                             CH.sub.3                                                                          H      C.sub.3 H.sub.7 (n)                                                                     (5)-C.sub.3 H.sub.7 (iso)                                                              H      724                      159  CH.sub.3                                                                          C.sub.4 H.sub.9 (tert)                                                               CH.sub.3                                                                          H      C.sub.8 H.sub.17 (n)                                                                    (5)-C.sub.3 H.sub.7 (iso)                                                              H      725                      160  CH.sub.3                                                                          CH.sub.3                                                                             CH.sub.3                                                                          H      C.sub.10 H.sub.21 (n)                                                                   (5)-C.sub.3 H.sub.7 (iso)                                                              H      724                      161  CH.sub.3                                                                          CH.sub.3                                                                             CH.sub.3                                                                          H      C.sub.18 H.sub.37 (n)                                                                   (5)-C.sub.3 H.sub.7 (iso)                                                              H      724                      162  CH.sub.3                                                                          CH.sub.3                                                                             CH.sub.3                                                                          H      C.sub.4 H.sub.9 (n)                                                                     (8)-OCH.sub.3                                                                          (5)-C.sub.3 H.sub.7                                                                  726o)                    163  CH.sub.3                                                                          CH.sub.3                                                                             CH.sub.3                                                                          H      C.sub.3 H.sub.7 (n)                                                                     (8)-OC.sub.7 H.sub.15 (n)                                                              (5)-C.sub.3 H.sub.7                                                                  726o)                    164  CH.sub.3                                                                          CH.sub.3                                                                             CH.sub.3                                                                          H      C.sub.2 H.sub.5 (n)                                                                     (8)-OC.sub.18 H.sub.37 (n)                                                             (5)-C.sub.3 H.sub.7                                                                  726o)                    165  CH.sub.3                                                                          CH.sub.3                                                                             CH.sub.3                                                                          H      C.sub.5 H.sub.11 (n)                                                                    (8)-OC.sub.2 H.sub.4 OC.sub.2                                                 H.sub.5  (5)-C.sub.3 H.sub.7                                                                  726o)                    166  CH.sub.3                                                                          CH.sub.3                                                                             CH.sub.3                                                                          H                                                                                     ##STR121##                                                                             (5)-C.sub.3 H.sub.7 (iso)                                                              H      735                      167  CH.sub.3                                                                          CH.sub.3                                                                             CH.sub.3                                                                          H                                                                                     ##STR122##                                                                             (5)-C.sub.3 H.sub.7 (iso)                                                              H      723                      168  CH.sub.3                                                                          CH.sub.3                                                                             CH.sub.3                                                                          H      H         H        H      704                      __________________________________________________________________________

                                      TABLE 12                                    __________________________________________________________________________     ##STR123##                                                                   Example          1,2-Alkylene Group      λ.sub.max                     No.  R.sup.28                                                                          R.sup.27                                                                          R.sup.26                                                                          for Forming Ring A                                                                      (position)-R.sup.2                                                                   (position)-R.sup.3                                                                   (nm)                                 __________________________________________________________________________    169  CH.sub.3                                                                          CH.sub.3                                                                          CH.sub.3                                                                          (CH.sub.2) .sub.3                                                                       (5)-CH.sub.3                                                                         H      732                                  170  CH.sub.3                                                                          CH.sub.3                                                                          CH.sub.3                                                                          (CH.sub.2) .sub.3                                                                       (6)-C.sub.3 H.sub.7 (iso)                                                            H      735                                  171  CH.sub.3                                                                          CH.sub.3                                                                          CH.sub.3                                                                          (CH.sub.2) .sub.4                                                                       H      H      733                                  172  CH.sub.3                                                                          CH.sub.3                                                                          CH.sub.3                                                                          (CH.sub.2) .sub.4                                                                       (5)-CH.sub.3                                                                         H      740                                  __________________________________________________________________________

                                      TABLE 13                                    __________________________________________________________________________     ##STR124##                                                                   Example          1,2-Alkylene Group             λ.sub.max              No.  R.sup.28                                                                          R.sup.27                                                                          R.sup.26                                                                          for Forming Ring B                                                                         (position)-R.sup.2                                                                       (position)-R.sup.3                                                                   (nm)                          __________________________________________________________________________    173  CH.sub.3                                                                          CH.sub.3                                                                          CH.sub.3                                                                          CHCHCHCH     (5)-C.sub.3 H.sub.7 (iso)                                                                H      773                           174  CH.sub.3                                                                          CH.sub.3                                                                          CH.sub.3                                                                          CHCHCHCH     (8)-(OC.sub.2 H.sub.4).sub.2OCH.sub.                                                     (5)-C.sub.3 H.sub.7 (iso)                                                            775                           175  CH.sub.3                                                                          CH.sub.3                                                                          CH.sub.3                                                                          CHCHCHCH     (6)-C.sub.3 H.sub.7 (iso)                                                                H      776                           176  CH.sub.3                                                                          CH.sub.3                                                                          CH.sub.3                                                                           ##STR125##  (5)-C.sub.3 H.sub.7 (iso)                                                                H      779                           177  CH.sub.3                                                                          CH.sub.3                                                                          CH.sub.3                                                                           ##STR126##  (5)-C.sub.3 H.sub.7 (iso)                                                                H      780                           178  CH.sub.3                                                                          CH.sub.3                                                                          CH.sub.3                                                                           ##STR127##  (5)-C.sub.3 H.sub.7 (iso)                                                                H      784                           179  CH.sub.3                                                                          CH.sub.3                                                                          CH.sub.3                                                                           ##STR128##  (5)-C.sub.3 H.sub.7 (iso)                                                                H      782                           180  CH.sub.3                                                                          CH.sub.3                                                                          CH.sub.3                                                                           ##STR129##  (5)-C.sub.3 H.sub.7 (iso)                                                                H      778                           __________________________________________________________________________

EXAMPLE 181

Ten milliliters of n-butyl alcohol was added to 37 mg of3,4-dihydroxy-3-cyclobutene-1,2-dione, and the mixture was heated toabout 100° C. to form a solution. To the solution were added 120 mg ofazuleno[1,2-b]thiophene and 15 ml of toluene, and the mixture wasstirred at 105 to 110° C. for about 20 minutes while azeotropicallyremoving the produced water. After cooling, the reaction mixture waspurified by column chromatography to obtain a compound of the formula:##STR130## This compound was not melted below 300° C., and itsabsorption spectrum in the chloroform solution showed the maximumabsorption at 775 nm.

EXAMPLE 182

In the same manner as described in Example 181 but replacing theazuleno[1,2-b]thiophene as used in Example 181 with the equimolar amountof 7-isopropylazuleno[1,2-b]thiophene, a compound of the followingformula was obtained: ##STR131## This compound had a melting point of224.5° to 226.0° C. and the maximum absorption wavelength in itschloroform solution was 783 nm.

EXAMPLE 183

In the same manner as described in Example 181 but replacing theazuleno[1,2-b]thiophene as used in Example 181 with the equimolar amountof 7-isopropylazuleno[1,2-b]1,2-dihydrothiophene, a compound of thefollowing formula was obtained: ##STR132## This compound had a meltingpoint of 219.0° to 220.5° C. and its absorption spectrum in a chloroformsolution showed the maximum absorption at 815 nm.

EXAMPLE 184

In the same manner as in Example 181 except for replacing theazuleno[1,2-b]thiophene as used in Example 181 with the equimolar amountof 7-isopropylazuleno[1,2-c]-1,3-dihydrothiophene, a compound of thefollowing formula was obtained: ##STR133## This compound had a meltingpoint of 249.5° to 250.5° C. and its absorption spectrum in thechloroform solution showed the maximum absorption at 746 nm.

EXAMPLE 185

In the same manner as described in Example 181 but replacing theazuleno[1,2-b]thiophene with the equimolar amount of7-isopropylazuleno[2,1-b]2,3-dihydrothiophene, a compound of thefollowing formula was obtained. ##STR134## This compound had a meltingpoint of 220.0° to 221.5° C. and its absorption spectrum in thechloroform solution showed the maximum absorption at 815 nm.

EXAMPLE 186

In the same manner as in Example 181 except for replacing theazuleno[1,2-b]thiophene as used in Example 181 with the equimolar amountof 6-isopropylazuleno[1,2-b]1,2-dihydrothiophene, a compound of thefollowing formula was obtained: ##STR135## This compound had a meltingpoint of 254.5° to 255.0° C., and its absorption spectrum in thechloroform solution showed the maximum absorption at 804 nm.

EXAMPLE 187

In the same manner as in Example 181 except for replacing theazuleno[1,2-b]thiophene as used in Example 181 with the equimolar amountof 7-isopropylazuleno[1,2-b]furan, a compound of the following formulawas obtained: ##STR136## This compound was not melted below 300° C., andits absorption spectrum in the chloroform solution showed the maximumabsorption at 760 nm.

EXAMPLE 188

In the same manner as in Example 181 but replacing theazuleno[1,2-b]thiophene with the equimolar amount of3-ethoxycarbonyl-8-isopropylazuleno[1,2-c]1,2,3,4-tetrahydropyridine, acompound of the following formula was obtained: ##STR137## This compoundhad a melting point of 219° to 220° C., and its absorption spectrum inthe chloroform solution showed the maximum absorption at 752 nm.

EXAMPLES 189 TO 263

In the same manner as described in Example 181, squarilium compoundsshown in Tables 14 to 17 were obtained. Their structures and the maximumabsorption wavelengths in their chloroform solutions are shown in Tables14 to 17.

                                      TABLE 14                                    __________________________________________________________________________     ##STR138##                                                                    No.Example                                                                         ##STR139##                                                                              (position)-R.sup.2                                                                   (position)-R.sup.3                                                                    ##STR140##     (position)-R.sup.2'                                                                   (position)-R.sup.3'                                                                  (nm)λ.                                                                sub.max           __________________________________________________________________________    189                                                                                 ##STR141##                                                                             (6)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR142##    (6')-C.sub.3 H.sub.7                                                                  Hiso)  772               190                                                                                 ##STR143##                                                                             (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR144##    (6')-C.sub.3 H.sub.7                                                                  Hiso)  778               191                                                                                 ##STR145##                                                                             (6)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR146##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  810               192                                                                                 ##STR147##                                                                             (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR148##    (6')-C.sub.3 H.sub.7                                                                  Hiso)  794               193                                                                                 ##STR149##                                                                             (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR150##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  799               194                                                                                 ##STR151##                                                                             (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR152##    H       H      779               195                                                                                 ##STR153##                                                                             H      H                                                                                      ##STR154##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  795               196                                                                                 ##STR155##                                                                             H      H                                                                                      ##STR156##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  761               197                                                                                 ##STR157##                                                                             H      H                                                                                      ##STR158##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  795               198                                                                                 ##STR159##                                                                             (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR160##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  765               199                                                                                 ##STR161##                                                                             (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR162##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  799               200                                                                                 ##STR163##                                                                             (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR164##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  781               201                                                                                 ##STR165##                                                                             (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR166##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  815               202                                                                                 ##STR167##                                                                             (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR168##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  781               203                                                                                 ##STR169##                                                                             H      H                                                                                      ##STR170##    (6')-C.sub.3 H.sub.7                                                                  Hiso)  790               204                                                                                 ##STR171##                                                                             (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR172##    (6')-C.sub.3 H.sub.7                                                                  Hiso)  794               205                                                                                 ##STR173##                                                                             (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR174##    (6')-C.sub.3 H.sub.7                                                                  Hiso)  775               206                                                                                 ##STR175##                                                                             (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR176##    (6')-C.sub.3 H.sub.7                                                                  Hiso)  810               207                                                                                 ##STR177##                                                                             (6)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR178##    (6')-C.sub.3 H.sub.7                                                                  Hiso)  788               208                                                                                 ##STR179##                                                                             (6)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR180##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  759               209                                                                                 ##STR181##                                                                             (6)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR182##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  794               210                                                                                 ##STR183##                                                                             (6)-C.sub.3 H.sub.7 (n)                                                              H                                                                                      ##STR184##    (6')-C.sub.3 H.sub.7                                                                  Hiso)  772               211                                                                                 ##STR185##                                                                             (6)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR186##    (6')-C.sub.3 H.sub.7                                                                  Hiso)  804               212                                                                                 ##STR187##                                                                             (4)-OCH.sub.3                                                                        (7)-C.sub.3 H.sub.7 (iso)                                                              ##STR188##    (4')-OCH.sub.3                                                                        (7')-C.sub.3 H.sub.7                                                          (iso)  785               213                                                                                 ##STR189##                                                                             (5)-C.sub.3 H.sub.7 (iso)                                                            (8')-CH.sub.3                                                                          ##STR190##    (5')-C.sub.3 H.sub.7                                                                  (8)-CH.sub.3                                                                         823               214                                                                                 ##STR191##                                                                             (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR192##    (6')-C.sub.3 H.sub.7                                                                  Hiso)  756               215                                                                                 ##STR193##                                                                             (5)-C.sub.3 H.sub.7 (iso)                                                            (8)-CH.sub.3                                                                           ##STR194##    (5')-C.sub.3 H.sub.7                                                                  (8')-CH.sub.3                                                                        800               216                                                                                 ##STR195##                                                                             (4)-CH.sub.3                                                                         (6)-CH.sub.3                                                                           ##STR196##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  795               217                                                                                 ##STR197##                                                                             (4)-CH.sub.3                                                                         (7)-CH.sub.3                                                                           ##STR198##    (4')-CH.sub.3                                                                         (7')-CH.sub.3                                                                        789               218                                                                                 ##STR199##                                                                             (4)-OC.sub.4 H.sub.9 (n)                                                             (7)-C.sub.3 H.sub.7 (iso)                                                              ##STR200##    (6')-C.sub.3 H.sub.7                                                                  Hiso)  776               219                                                                                 ##STR201##                                                                             H      H                                                                                      ##STR202##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  768               220                                                                                 ##STR203##                                                                             (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR204##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  772               221                                                                                 ##STR205##                                                                             (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR206##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  788               222                                                                                 ##STR207##                                                                             (6)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR208##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  753               223                                                                                 ##STR209##                                                                             (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR210##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  788               224                                                                                 ##STR211##                                                                             (6)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR212##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  782               225                                                                                 ##STR213##                                                                             (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR214##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  772               226                                                                                 ##STR215##                                                                             (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR216##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  768               227                                                                                 ##STR217##                                                                             (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR218##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  787               228                                                                                 ##STR219##                                                                             (6)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                      ##STR220##    (7')-C.sub.3 H.sub.7                                                                  Hiso)  766               __________________________________________________________________________

                                      TABLE 15                                    __________________________________________________________________________     ##STR221##                                                                    No.Ex.                                                                           ##STR222##    R.sup.2tion)-(posi-                                                                R.sup.3tion)-(posi-                                                                R.sup.5'                                                                            R.sup.1'  R.sup.2'(position)-                                                                   R.sup.3'tion)-(posi-                                                               R.sup.4'tion)-(po                                                            si-  (nm)λ.                                                                sub.max           __________________________________________________________________________    229                                                                               ##STR223##   H    H   H      H         (8')-CH.sub.3                                                                         (6')-CH.sub.3                                                                      (4')- CH.sub.3                                                                    768               230                                                                               ##STR224##   (7)- C.sub.3 H.sub.7 (iso)                                                         H   C.sub.2 H.sub.5                                                                      CH.sub.3  (5')- C.sub.3 H.sub.7 (iso)                                                           H    H   772               231                                                                               ##STR225##   (7)- C.sub.3 H.sub.7 (iso)                                                         H   C.sub.3 H.sub.7 (n)                                                                  C.sub.2 H.sub.5                                                                         (5')- C.sub.3 H.sub.7 (iso)                                                           H    H   788               232                                                                               ##STR226##   (7)- C.sub.3 H.sub.7 (iso)                                                         H   C.sub.4 H.sub.9 (n)                                                                  C.sub.3 H.sub.7 (n)                                                                     (5')- C.sub.3 H.sub.7 (iso)                                                           H    H   756               233                                                                               ##STR227##   (7)- C.sub.3 H.sub.7 (iso)                                                         H   C.sub.6 H.sub.13 (n)                                                                 C.sub.5 H.sub.11 (n)                                                                    (6')- C.sub.3 H.sub.7 (iso)                                                           H    H   791               234                                                                               ##STR228##   (6)- C.sub.3 H.sub.7 (iso)                                                         H   C.sub.8 H.sub.17 (n)                                                                 C.sub.7 H.sub.15 (n)                                                                    (6')- C.sub.3 H.sub.7 (iso)                                                           H    H   782               235                                                                               ##STR229##   (7)- C.sub.3 H.sub.7 (iso)                                                         H   C.sub.5 H.sub.11 (n)                                                                 C.sub. 4 H.sub.9 (n)                                                                    (5')- C.sub.3 H.sub.7 (iso)                                                           H    H   760               236                                                                               ##STR230##   H    H   H      CH.sub.3  (5')- C.sub.3 H.sub.7 (iso)                                                           H    H   761               237                                                                               ##STR231##   (7)- C.sub.3 H.sub.7 (iso)                                                         H   C.sub.13 H.sub.27 (n)                                                                C.sub.12 H.sub.25 (n)                                                                   (5')- C.sub.3 H.sub.7 (iso)                                                           H    H   772               238                                                                               ##STR232##   H    H   H      C.sub.3 H.sub.7 (n)                                                                     (5')- C.sub.3 H.sub.7 (iso)                                                           H    H   752               239                                                                               ##STR233##   (7)- C.sub.3 H.sub.7 (iso)                                                         H   H      C.sub.8 H.sub.17 (n)                                                                    (5')- C.sub.3 H.sub.7 (iso)                                                           H    H   757               240                                                                               ##STR234##   (7)- C.sub.3 H.sub.7 (iso)                                                         H   H      C.sub.10 H.sub.21 (n)                                                                   (5')- C.sub.3 H.sub.7 (iso)                                                           H    H   772               241                                                                               ##STR235##   (7)- C.sub.3 H.sub.7 (iso)                                                         H   H      C.sub.18 H.sub.37 (n)                                                                   (5')- C.sub.3 H.sub.7 (iso)                                                           H    H   737               242                                                                               ##STR236##   (7)- C.sub.3 H.sub.7 (iso)                                                         H   H      C.sub.4 H.sub.9 (n)                                                                     (8')-OCH.sub.3                                                                        (5')- C.sub.3 H.sub.7                                                         (iso)                                                                              H   774               243                                                                               ##STR237##   (6)- C.sub.3 H.sub.7 (iso)                                                         H   H      C.sub.3 H.sub.7 (n)                                                                     (8')- OC.sub.7 H.sub.15                                                               (5')- C.sub.3 H.sub.7                                                         (iso)                                                                              H   768               244                                                                               ##STR238##   (7)- C.sub.3 H.sub.7 (iso)                                                         H   H      C.sub.2 H.sub.5                                                                         (8')- OC.sub.18 H.sub.37                                                              (5')- C.sub.3 H.sub.7                                                         (iso)                                                                              H   746               245                                                                               ##STR239##   (7)- C.sub.3 H.sub.7 (iso)                                                         H   H      C.sub.5 H.sub.11 (n)                                                                    (8')- OC.sub.2 H.sub.4                                                        OC.sub.2 H.sub.5                                                                      (5')- C.sub.3 H.sub.7                                                         (iso)                                                                              H   756               246                                                                               ##STR240##   (7)- C.sub.3 H.sub.7 (iso)                                                         H   H                                                                                     ##STR241##                                                                             (5')- C.sub.3 H.sub.7 (iso)                                                           H    H   754               247                                                                               ##STR242##   H    H   H                                                                                     ##STR243##                                                                             (5')- C.sub.3 H.sub.7 (iso)                                                           H    H   750               248                                                                               ##STR244##   H    H   H      H         H       H    H   743               249                                                                               ##STR245##   (7)- C.sub.3 H.sub.7 (iso)                                                         H   H      H         (8')-CH.sub.3                                                                         (6')-CH.sub.3                                                                      (4')- CH.sub.3                                                                    752               250                                                                               ##STR246##   (7)- C.sub.3 H.sub.7 (iso)                                                         H   H      CH.sub.3  (4')-CH.sub.3                                                                         (7')- C.sub.3 H.sub.7                                                         (iso)                                                                              H   792               __________________________________________________________________________

                                      TABLE 16                                    __________________________________________________________________________     ##STR247##                                                                    No.pleam-Ex-                                                                     ##STR248##                                                                             (position)-R.sup.2                                                                   (position)-R.sup.3                                                                    for Forming Ring A'1',2'-Alkylene                                                         (position)-R.sup.2'                                                                  (position)-R.sup.3'                                                                  (position)-R.sup.4'                                                                  (nm)λ.                                                                sub.max           __________________________________________________________________________    251                                                                               ##STR249##                                                                            (7)-C.sub.3 H.sub.7 (iso)                                                            H      (CH.sub.2) .sub.3                                                                          (5')-CH.sub.3                                                                        H      H      749               252                                                                               ##STR250##                                                                            (7)-C.sub.3 H.sub.7 (iso)                                                            H      (CH.sub.2) .sub.3                                                                          (6')-C.sub.3 H.sub.7 (iso)                                                           H      H      783               253                                                                               ##STR251##                                                                            (6)-C.sub.3 H.sub.7 (iso)                                                            H      (CH.sub.2) .sub.4                                                                          H      H      H      781               254                                                                               ##STR252##                                                                            H      H      (CH.sub.2) .sub.4                                                                          (5')-CH.sub.3                                                                        H       H     756               __________________________________________________________________________

                                      TABLE 17                                    __________________________________________________________________________     ##STR253##                                                                    No.pleam-Ex-                                                                     ##STR254##                                                                             (position)-R.sup.2                                                                   (position)-R.sup.3                                                                   for Forming Ring B'1',2'-Alkylene                                                          (position)-R.sup.2'                                                                     (position)-R.sup.3'                                                                  R.sup.4'tion)-(po                                                            si-  (nm)λ.                                                                sub.max           __________________________________________________________________________    255                                                                               ##STR255##                                                                            (7)-C.sub.3 H.sub.7 (iso)                                                            H      CHCHCHCH     (5')-C.sub.3 H.sub.7 (iso)                                                              H      H   793               256                                                                               ##STR256##                                                                            (7)-C.sub.3 H.sub.7 (iso)                                                            H      CHCHCHCH     (8')-(OC.sub.2 H.sub.4).sub.2                                                 OCH.sub.3 (5')-C.sub.3 H.sub.7                                                          (iso)  H   805               257                                                                               ##STR257##                                                                            (7)-C.sub.3 H.sub.7 (iso)                                                            H      CHCHCHCH     (6')-C.sub.3 H.sub.7 (iso)                                                              H      H   806               258                                                                               ##STR258##                                                                            H      H                                                                                     ##STR259##  (5')-C.sub.3 H.sub.7 (iso)                                                              H      H   807               259                                                                               ##STR260##                                                                            (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                     ##STR261##  (5')-C.sub.3 H.sub.7 (iso)                                                              H      H   812               260                                                                               ##STR262##                                                                            (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                     ##STR263##  (5')-C.sub.3 H.sub.7 (iso)                                                              H      H   832               261                                                                               ##STR264##                                                                            (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                     ##STR265##  (5')-C.sub.3 H.sub.7 (iso)                                                              H      H   795               262                                                                               ##STR266##                                                                            (7)-C.sub.3 H.sub.7 (iso)                                                            H                                                                                     ##STR267##  (5')-C.sub.3 H.sub.7 (iso)                                                              H      H   826               263                                                                               ##STR268##                                                                            (6)-C.sub.3 H.sub.7 (iso)                                                            H      CHCHCHCH     (6' )-C.sub.3 H.sub.7 (iso)                                                             H      H   815               __________________________________________________________________________

EXAMPLE 264

Thirty milliliters of n-butyl alcohol was added to 15 mg of3,4-dihydroxy-3-cyclobutene-1,2-dione, and the mixture was heated toabout 100° C. to form a solution. To the solution were added 50 mg of1-n-heptadecylazulene and 15 ml of toluene, and the mixture was stirredat 105° to 110° C. for about 20 minutes while azeotropically removingthe produced water. After cooling, the reaction mixture was purified bycolumn chromatography to obtain a compound of the formula: ##STR269##The absorption spectrum of this compound in chloroform is shown inFIG. 1. The maximum absorption wavelength was 726 nm.

EXAMPLES 265 TO 333

In the same manner as described in Example 264, squarilium compounds asshown in Tables 18 to 20 below were prepared. Their structures and themaximum absorption wavelengths in chloroform are shown in Tables 18 to20.

                                      TABLE 18                                    __________________________________________________________________________     ##STR270##                                                                                    (posi-                                                                             (posi-                                                  Ex.              tion)-                                                                             tion)-                  (position)-                                                                         (position)-                                                                           λ.sub.m                                                                ax                No.                                                                              R.sup.5                                                                              R.sup.1                                                                              R.sup.2                                                                            R.sup.3                                                                           R.sup.5'                                                                             R.sup.1'     R.sup.2'                                                                            R.sup.3'                                                                              (nm)              __________________________________________________________________________    265                                                                              H      C.sub.14 H.sub.29 (n)                                                                H    H   H      C.sub.14 H.sub.29 (n)                                                                      H     H       712               266                                                                              H      C.sub.18 H.sub.37 (n)                                                                H    H   H      C.sub.18 H.sub.37 (n)                                                                      H     H       712               267                                                                              H      C.sub.20 H.sub.41 (n)                                                                H    H   H      C.sub.20 H.sub.41 (n)                                                                      H     H       712               268                                                                              H      C.sub.23 H.sub.47 (n)                                                                H    H   H      C.sub.23 H.sub.47 (n)                                                                      H     H       712               269                                                                              H      C.sub.17 H.sub.35 (n)                                                                (5)-CH.sub.3                                                                       H   H      C.sub.17 H.sub.35 (n)                                                                      (5')-CH.sub.3                                                                       H       726               270                                                                              H      C.sub.20 H.sub.41 (n)                                                                (5)-CH.sub.3                                                                       H   H      C.sub.20 H.sub.41 (n)                                                                      (5')-CH.sub.3                                                                       H       726               271                                                                              H      C.sub.14 H.sub.29 (n)                                                                (5)- H   H      C.sub.14 H.sub.29 (n)                                                                      (5')- H       726                                C.sub.3 H.sub.7 (iso)        C.sub.3 H.sub.7 (iso)           272                                                                              H      C.sub.19 H.sub.39 (n)                                                                (5)- H   H      C.sub.19 H.sub.39 (n)                                                                      (5')- H       726                                C.sub.3 H.sub.7 (iso)        C.sub.3 H.sub.7 (iso)           273                                                                              H      C.sub.24 H.sub.49 (n)                                                                (5)- H   H      C.sub.24 H.sub.49 (n)                                                                      (5')- H       726                                C.sub.3 H.sub.7 (iso)        C.sub.3 H.sub.7 (iso)           274                                                                              H      C.sub.18 H.sub.37 (n)                                                                (6)-CH.sub.3                                                                       H   H      C.sub.18 H.sub.37 (n)                                                                      (6')-CH.sub.3                                                                       H       732               275                                                                              H      C.sub.21 H.sub.43 (n)                                                                (6)-CH.sub.3                                                                       H   H      C.sub.21 H.sub.43 (n)                                                                      (6')-CH.sub.3                                                                       H       732               276                                                                              H      C.sub.15 H.sub.31 (n)                                                                (6)- H   H      C.sub.15 H.sub.31 (n)                                                                      (6')- H       732                                C.sub.3 H.sub.7 (iso)        C.sub.3 H.sub.7 (iso)           277                                                                              H      C.sub.17 H.sub.35 (n)                                                                (6)- H   H      C.sub.17 H.sub.35 (n)                                                                      (6')- H       732                                C.sub.3 H.sub.7 (iso)        C.sub.3 H.sub.7 (iso)           278                                                                              C.sub.15 H.sub.31 (n)                                                                C.sub.14 H.sub.29 (n)                                                                (5)- H   C.sub.15 H.sub.31 (n)                                                                C.sub.14 H.sub.29 (n)                                                                      (5')- H       758                                C.sub.3 H.sub.7 (iso)        C.sub.3 H.sub.7 (iso)           279                                                                              C.sub.17 H.sub.35 (n)                                                                C.sub.16 H.sub.33 (n)                                                                (5)- H   C.sub.17 H.sub.35 (n)                                                                C.sub.16 H.sub.33 (n)                                                                      (5')- H       758                                C.sub.3 H.sub.7 (iso)        C.sub.3 H.sub.7 (iso)           280                                                                              H      C.sub.23 H.sub.47 (n)                                                                H    H   C.sub.2 H.sub.5                                                                      CH.sub.3     (5')- H       735                                                             C.sub.3 H.sub.7 (iso)           281                                                                              H      C.sub.19 H.sub.39 (n)                                                                H    H   C.sub.3 H.sub.7 (n)                                                                  C.sub.2 H.sub.5                                                                            (5')- H       735                                                             C.sub.3 H.sub.7 (iso)           282                                                                              H      C.sub.15 H.sub.31 (n)                                                                (5)-CH.sub.3                                                                       H   C.sub.3 H.sub.7 (n)                                                                  C.sub.2 H.sub.5                                                                            (5')- H       742                                                             C.sub.3 H.sub.7 (iso)           283                                                                              H      C.sub.16 H.sub.33 (n)                                                                (5)- H   C.sub.4 H.sub.9 (n)                                                                  C.sub.3 H.sub.7 (n)                                                                        (5')- H       742                                C.sub.3 H.sub.7 (iso)        C.sub.3 H.sub.7 (iso)           284                                                                              H      C.sub.19 H.sub.39 (n)                                                                (5)- H   C.sub.8 H.sub.17 (n)                                                                 C.sub.7 H.sub.15 (n)                                                                       (5')-CH.sub.3                                                                       H       742                                C.sub.3 H.sub.7 (iso)                                        285                                                                              H      C.sub.21 H.sub.43 (n)                                                                (5)- H   C.sub.2 H.sub.5                                                                      CH.sub.3     (5')-CH.sub.3                                                                       H       742                                C.sub.3 H.sub.7 (iso)                                        286                                                                              H      C.sub.17 H.sub.35 (n)                                                                (6)-CH.sub.3                                                                       H   C.sub.4 H.sub.9 (n)                                                                  C.sub.3 H.sub. 7 (n)                                                                       (5')- H       745                                                             C.sub.3 H.sub.7 (iso)           287                                                                              H      C.sub.20 H.sub.41 (n)                                                                (6)- H   C.sub.5 H.sub.11 (n)                                                                 C.sub.4 H.sub.9 (n)                                                                        (5')-CH.sub.3                                                                       H       745                                C.sub.3 H.sub.7 (iso)                                        288                                                                              H      C.sub.18 H.sub.37 (n)                                                                (6)- H   C.sub.6 H.sub.13 (n)                                                                 C.sub.5 H.sub.11 (n)                                                                       (5')- H       745                                C.sub.3 H.sub.7 (iso)        C.sub.3 H.sub.7 (iso)           289                                                                              H      C.sub.16 H.sub.33 (n)                                                                H    H   H                                                                                     ##STR271##  (5')- C.sub.3 H.sub.7                                                               Hiso)   730               290                                                                              H      C.sub.20 H.sub.41 (n)                                                                H    H   H                                                                                     ##STR272##  (5')- C.sub.3 H.sub.7                                                               Hiso)   719               291                                                                              H      C.sub.24 H.sub.49 (n)                                                                (5)-CH.sub.3                                                                       H   H                                                                                     ##STR273##  (5')- C.sub.3 H.sub.7                                                               Hiso)   737               292                                                                              H      C.sub.19 H.sub.39 (n)                                                                (5)- C.sub.3 H.sub.7 (iso)                                                         H   H                                                                                     ##STR274##  (5')-CH.sub.3                                                                       H       736               293                                                                              H      C.sub.15 H.sub.31 (n)                                                                (5)- C.sub.3 H.sub.7 (iso)                                                         H   H                                                                                     ##STR275##  (6')- C.sub.3 H.sub.7                                                               Hiso)   728               294                                                                              H      C.sub.23 H.sub.47 (n)                                                                (5)- C.sub.3 H.sub.7 (iso)                                                         H   H                                                                                     ##STR276##  (5')- C.sub.3 H.sub.7                                                               Hiso)   726               295                                                                              H      C.sub.17 H.sub.35 (n)                                                                (6)-CH.sub.3                                                                       H   H                                                                                     ##STR277##  (5')- C.sub.3 H.sub.7                                                               Hiso)   740               296                                                                              H      C.sub.14 H.sub.29 (n)                                                                (6)- C.sub.3 H.sub.7 (iso)                                                         H   H                                                                                     ##STR278##  (5')- C.sub.3 H.sub. 7                                                        (iso) H       740               297                                                                              H      C.sub.22 H.sub.45 (n)                                                                (6)- C.sub.3 H.sub.7 (iso)                                                         H   H                                                                                     ##STR279##  (6')- C.sub.3 H.sub.7                                                               Hiso)   729               298                                                                              H      C.sub.17 H.sub.35 (n)                                                                H    H   H      C.sub.5 H.sub.11 (n)                                                                       (5')- (8')-OCH.sub.3                                                                        721                                                             C.sub.3 H.sub.7 (iso)           299                                                                              H      C.sub.24 H.sub.49 (n)                                                                H    H   H      C.sub.4 H.sub.9 (n)                                                                        (5')- (8')-   721                                                             C.sub.3 H.sub.7 (iso)                                                               OC.sub.7 H.sub.15 (n)     300                                                                              H      C.sub.20 H.sub.41 (n)                                                                (5)-CH.sub.3                                                                       H   H      C.sub.6 H.sub.13 (n)                                                                       (5')- (8')-OCH.sub.3                                                                        728                                                             C.sub.3 H.sub.7 (iso)           301                                                                              H      C.sub.15 H.sub.31 (n)                                                                (5)- H   H      C.sub.4 H.sub.9 (n)                                                                        (5')-C.sub.3 H.sub.7                                                                (8')-OCH.sub.3                                                                        728                                C.sub.3 H.sub.7 (iso)                                        302                                                                              H      C.sub.14 H.sub.29 (n)                                                                (5)- H   H      CH.sub.3     (4')-CH.sub.3                                                                       (7')-   747                                C.sub.3 H.sub.7 (iso)              C.sub.3 H.sub.7 (iso)     303                                                                              H      C.sub.21 H.sub.43 (n)                                                                (5)- H   H      C.sub.5 H.sub.11 (n)                                                                       (5')- (8')-   728                                C.sub.3 H.sub.7 (iso)        C.sub.3 H.sub.7 (iso)                                                               OC.sub.2 H.sub.4                                                              OC.sub.2 H.sub.5          304                                                                              H      C.sub.16 H.sub.33 (n)                                                                (6)-CH.sub.3                                                                       H   H      C.sub.3 H.sub.7 (n)                                                                        (5')- (8')-OCH.sub.3                                                                        731                                                             C.sub.3 H.sub.7 (iso)           305                                                                              H      C.sub.23 H.sub.47 (n)                                                                (6)- H   H      C.sub.5 H.sub.11 (n)                                                                       (5')- (8')-OCH.sub.3                                                                        731                                C.sub.3 H.sub.7 (iso)        C.sub.3 H.sub.7 (iso)           306                                                                              H      C.sub.19 H.sub.39 (n)                                                                (6)- H   H      C.sub.4 H.sub.9 (n)                                                                        (5')- (8')-   731                                C.sub.3 H.sub.7 (iso)        C.sub.3 H.sub.7 (iso)                                                               OC.sub.7 H.sub.15 (n)     307                                                                              H      C.sub.20 H.sub.41 (n)                                                                H    H   H      C.sub.14 H.sub.29 (n)                                                                      (5')- H       719                                                             C.sub.3 H.sub.7 (iso)           308                                                                              H      C.sub.23 H.sub.47 (n)                                                                H    H   H      C.sub.19 H.sub.39 (n)                                                                      (5')- H       719                                                             C.sub.3 H.sub.7 (iso)           309                                                                              H      C.sub.14 H.sub.29 (n)                                                                (5)-CH.sub.3                                                                       H   H      C.sub.17 H.sub.35 (n)                                                                      (6')-CH.sub.3                                                                       H       729               310                                                                              H      C.sub.19 H.sub.39 (n)                                                                (5)- H   H      C.sub.20 H.sub.41 (n)                                                                      (5')-CH.sub.3                                                                       H       726                                C.sub.3 H.sub.7 (iso)                                        311                                                                              H      C.sub.21 H.sub.43 (n)                                                                (5)- H   H      C.sub.15 H.sub.31 (n)                                                                      H     H       719                                C.sub.3 H.sub.7 (iso)                                        312                                                                              H      C.sub.25 H.sub.51 (n)                                                                (5)- H   H      C.sub.14 H.sub.29 (n)                                                                      H     H       719                                C.sub.3 H.sub.7 (iso)                                        313                                                                              H      C.sub.16 H.sub.33 (n)                                                                (6)-CH.sub.3                                                                       H   H      C.sub.24 H.sub.49 (n)                                                                      (5')- H       729                                                             C.sub.3 H.sub.7 (iso)           314                                                                              H      C.sub.15 H.sub.31 (n)                                                                (6)- H   H      C.sub.19 H.sub.39 (n)                                                                      (5')- H       729                                C.sub.3 H.sub.7 (iso)        C.sub.3 H.sub.7 (iso)           315                                                                              H      C.sub.18 H.sub.37 (n)                                                                (6)- H   H      C.sub.14 H.sub.29 (n)                                                                      (5')-CH.sub.3                                                                       H       729                                C.sub.3 H.sub.7 (iso)                                        __________________________________________________________________________

                                      TABLE 19                                    __________________________________________________________________________     ##STR280##                                                                   Example                        1',2'-Alkylene Group          λ.sub.                                                                max               No.  R.sup.5                                                                           R.sup.1                                                                              (position)-R.sup.2                                                                    (position)-R.sup.3                                                                   for Forming Ring B                                                                          (position)-R.sup.2'                                                                   (position)-R.sup.3'                                                                  (nm)              __________________________________________________________________________    316   H  C.sub.15 H.sub.31 (n)                                                                H       H                                                                                     ##STR281##   (5')-C.sub.3 H.sub.7                                                                  Hiso)  774               317  H   C.sub.25 H.sub.51 (n)                                                                H       H                                                                                     ##STR282##   (5')-C.sub.3 H.sub.7                                                                  Hiso)  774               318  H   C.sub.17 H.sub.35 (n)                                                                (5)-CH.sub.3                                                                          H      CHCHCHCH      (5')-C.sub.3 H.sub.7                                                                  Hiso)  775               319  H   C.sub.23 H.sub.47 (n)                                                                (5)-C.sub.3 H.sub.7 (iso)                                                             H                                                                                     ##STR283##   (6')-C.sub.3 H.sub.7                                                                  Hiso)  784               320  H   C.sub.19 H.sub.39 (n)                                                                (5)-C.sub.3 H.sub.7 (iso)                                                             H                                                                                     ##STR284##   (5')-C.sub.3 H.sub.7                                                                  Hiso)  781               321  H   C.sub.21 H.sub.43 (n)                                                                (5)-C.sub.3 H.sub.7 (iso)                                                             H                                                                                     ##STR285##   (5')-C.sub.3 H.sub.7                                                                  Hiso)  783               322  H   C.sub.18 H.sub.37 (n)                                                                (6)-CH.sub.3                                                                          H                                                                                     ##STR286##   (5')-C.sub.3 H.sub.7                                                                  Hiso)  778               323  H   C.sub.20 H.sub.41 (n)                                                                (6)-C.sub.3 H.sub.7 (iso)                                                             H                                                                                     ##STR287##   (5')-C.sub.3 H.sub.7                                                                  Hiso)  784               324  H   C.sub.16 H.sub.33 (n)                                                                (6)-C.sub.3 H.sub.7 (iso)                                                             H                                                                                     ##STR288##   (6')-C.sub.3 H.sub.7                                                                  Hiso)  787               __________________________________________________________________________

                                      TABLE 20                                    __________________________________________________________________________     ##STR289##                                                                   Example                          1',2'-Alkylene Group        λ.sub.                                                                max               No.  R.sup.5                                                                           R.sup.1 (position)-R.sup.2                                                                    (position)-R.sup.3                                                                    for Forming Ring A                                                                       (position)-R.sup.2'                                                                   (position)-R.sup.3'                                                                   (nm)              __________________________________________________________________________    325  H   C.sub.24 H.sub.49 (n)                                                                 H       H       (CH.sub.2 ) .sub.3                                                                       (5')-C.sub.3 H.sub.7 (iso)                                                            H       727               326  H   C.sub.22 H.sub.45 (n)                                                                 H       H       (CH.sub.2 ) .sub.4                                                                       (5')-CH.sub.3                                                                         H       735               327  H   C.sub.14 H.sub.29 (n)                                                                 (5)-CH.sub.3                                                                          H       (CH.sub.2 ) .sub.4                                                                       (5')-C.sub.3 H.sub.7 (iso)                                                            H       742               328  H   C.sub.17 H.sub.35 (n)                                                                 (5)-C.sub.3 H.sub.7 (iso)                                                             H       (CH.sub.2 ) .sub.4                                                                       (5')-C.sub.3 H.sub.7 (iso)                                                            H       742               329  H   C.sub.20 H.sub.41 (n)                                                                 (5)-C.sub.3 H.sub.7 (iso)                                                             H       (CH.sub.2 ) .sub.3                                                                       (5')-CH.sub.3                                                                         H       734               330  H   C.sub.23 H.sub.47 (n)                                                                 (5)-C.sub.3 H.sub.7 (iso)                                                             H       (CH.sub.2 ) .sub.4                                                                       (6')-C.sub.3 H.sub.7 (iso)                                                            H       744               331   H  C.sub.15 H.sub.31 (n)                                                                 (6)-CH.sub.3                                                                          H       (CH.sub.2 ) .sub.4                                                                       (5')-C.sub.3 H.sub.7 (iso)                                                            H       745               332  H   C.sub.18 H.sub.37 (n)                                                                 (6)-C.sub.3 H.sub.7 (iso)                                                             H       (CH.sub.2 ) .sub.4                                                                       (5')-C.sub.3 H.sub.7 (iso)                                                            H       745               333  H   C.sub.21 H.sub.43 (n)                                                                 (6)-C.sub.3 H.sub.7 (iso)                                                             H       (CH.sub.2 ) .sub.4                                                                       (6')-C.sub.3 H.sub.7 (iso)                                                            H       747               __________________________________________________________________________

While the invention has been described in detail and with reference tospecific embodiments thereof, it will be apparent to one skilled in theart that various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

What is claimed is:
 1. A squarilium compound represented by the formula (I): ##STR290## wherein X represents ##STR291## and Y represents ##STR292## wherein R¹ represents a hydrogen atom, a C₁₋₂₅ alkyl group, a phenyl group which is or is not substituted by a C₁₋₂₅ alkyl group, a C₁₋₁₃ alkoxy group, or halogen atom, a naphthyl group, a benzyl group which is or is not substituted by an alkyl group, an alkoxy group or a halogen atom, or a phenethyl group; R², R³ and R⁴ each represents a hydrogen atom, a C₁₋₅ alkyl group or an alkoxy group having total carbon number of 1 to 20 which is or is not substituted by an alkoxy group; R⁵ represents a hydrogen atom or a C₁₋₁₃ alkyl group; ring A represents a cyclic alkylene of 5 or 6 members which is not substituted by an alkyl group; ring B represents an aromatic ring or an 1,2-alkenylene ring which are or are not substituted by a halogen atom and are not substituted by an alkyl group or alkoxy group; and ring C represents a heterocyclic ring containing one of a nitrogen atom, an oxygen atom and a sulfur atom and said heterocyclic ring is not substituted by an alkyl group; with the proviso that X and Y are not the same when either one of them represents ##STR293##
 2. A squarilium compound represented by the formula (I): ##STR294## wherein X represents ##STR295## wherein R¹ represents a hydrogen atom, a C₁₋₂₅ alkyl group, a phenyl group or a benzyl group; R², r³ and R⁴ each represents a hydrogen atom, an alkyl group or an alkoxy group having 1 to 13 carbon atoms which is or is not substituted by an alkoxy group; r⁵ represents a hydrogen atom or a C₁₋₂₀ alkyl group; ring A represents a cyclic alkylene of 5 or 6 members and is not substituted by an alkyl group; ring B represents an 1,2-alkenylene ring of 6 members which is not substituted by an alkyl group or an alkoxy group; and ring C represents a heterocyclic ring of 5 or 6 members containing one of a nitrogen atom, an oxygen atom and a sulfur atom and said heterocyclic ring is not substituted by alkyl group; and Y represents ##STR296## wherein R², R³ and ring C are as defined above in this claim.
 3. A squarilium compound as in claim 2, wherein at least one of X and Y represents a group selected from the group (I) and (II), ##STR297## wherein R¹⁹ represents a hydrogen atom, a methyl group or an isopropyl group; R²² and R²³ each represents a hydrogen atom, an alkyl group having from 1 to 13 carbon atoms or an alkoxy-substituted or unsubstituted alkoxy group having from 1 to 13 carbon atoms; R³³ and R³⁴ each represents a hydrogen atom, a methyl group, or a phenyl group; and R³⁵ represents a hydrogen atom or an alkoxycarbonyl group; with the proviso that R¹⁹ is at the 6- or 7-position, and at least one of R¹⁹, R²² and R²³ represents a hydrogen atom, ##STR298## wherein R¹⁹ is as defined above in this claim; R³⁵ is as defined above; R³⁶ and R³⁷ each represents a hydrogen atom, a halogen atom, an alkoxy group, an alkylamino group, an alkoxycarbonyl group or a cyano group; with the proviso that R¹⁹ is at the 7- or 8-position.
 4. A squarilium compound represented by the formula ##STR299## wherein ring C represents a heterocyclic ring containing one of a nitrogen atom, an oxygen atom or a sulfur atom and said heterocyclic ring is not substituted by an alkyl group and R², R³ and R⁴ each represents a hydrogen atom, an alkyl group or an alkoxy-substituted or unsubstituted alkoxy group.
 5. A squarilium compound as in claim 4, wherein ring C represents a five or six-membered heterocyclic ring containing a sulfur atom, R² represents a hydrogen atom and R³ and R⁴ each represents a hydrogen atom, an alkyl group or an alkoxy group.
 6. A squarilium compound as in claim 5, wherein the compound is represented by the formula: ##STR300##
 7. A squarilium compound as in claim 5, wherein the compound is represented by the formula: ##STR301##
 8. A liquid crystal composition comprising a host liquid crystalline material and further comprising a squarilium compound as in claim
 1. 9. A liquid crystal composition comprising a host liquid crystalline material and further comprising a squarilium compound as in claim
 2. 10. A squarilium compound as in claim 2, wherein Y represents ##STR302## wherein ring C represents a heterocyclic ring containing a sulfur atom and R² and R³ are defined in claim
 2. 11. A squarilium compound as in claim 2, wherein X and Y each represents ##STR303## wherein ring C represents a heterocyclic ring containing a sulfur atom and R² and R³ each represents a hydrogen atom, an alkyl group or an alkoxy group.
 12. A squarilium compound as in claim 5, wherein ring C represents a thiophene or dihydrothiophene ring.
 13. A squarilium compound as in claim 5, wherein ring C represents a dihydrothiophene ring; R² is a hydrogen atom and R³ is an alkyl group. 